(Pyrovalerone) Analogues: A Promising Class of ... - ACS Publications

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J. Med. Chem. 2006, 49, 1420-1432

1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one (Pyrovalerone) Analogues: A Promising Class of Monoamine Uptake Inhibitors Peter C. Meltzer,*,† David Butler,† Jeffrey R. Deschamps,‡ and Bertha K. Madras§ Organix Inc., 240 Salem Street, Woburn, Massachusetts 01801, NaVal Research Laboratory, Washington, D.C. 20375, and Department of Psychiatry, HarVard Medical School and New England Regional Primate Research Center, Southborough, Massachusetts 01772 ReceiVed August 11, 2005

Dopamine, serotonin, and norepinephrine are essential for neurotransmission in the mammalian system. These three neurotransmitters have been the focus of considerable research because the modulation of their production and their interaction at monoamine receptors has profound effects upon a multitude of pharmacological outcomes. Our interest has focused on neurotransmitter reuptake mechanisms in a search for medications for cocaine abuse. Herein we describe the synthesis and biological evaluation of an array of 2-aminopentanophenones. This array has yielded selective inhibitors of the dopamine and norepinephrine transporters with little effect upon serotonin trafficking. A subset of compounds had no significant affinity at 5HT1A, 5HT1B, 5HT1C, D1, D2, or D3 receptors. The lead compound, racemic 1-(4-methylphenyl)-2pyrrolidin-1-yl-pentan-1-one 4a, was resolved into its enantiomers and the S isomer was found to be the most biologically active enantiomer. Among the most potent of these DAT/NET selective compounds are the 1-(3,4-dichlorophenyl)- (4u) and the 1-naphthyl- (4t) 2-pyrrolidin-1-yl-pentan-1-one analogues. Introduction The endogenous monoamines, dopamine (DA), serotonin, and norepinephrine (NE) are essential for neurotransmission in the mammalian system. These three neurotransmitters, their biological receptors, and their reuptake mechanisms are the focus of considerable research because modulation of their production and their interaction at monoamine receptors has profound effects upon a multitude of pharmacological outcomes.1-8 Dopamine, serotonin, and norepinephrine are released into the synapse where their concentrations are regulated, at least in part, by reuptake proteins located in the presynaptic membrane.9,10 These reuptake mechanisms have been termed the dopamine transporter (DAT), serotonin transporter (SERT), and the norepinephrine transporter (NET). The DAT is the target of numerous therapeutic agents, such as Ritalin (methylphenidate), Adderral (amphetamine), Wellbutrin, and Zyban (bupropion). Our interest has focused on the DAT in a search for medications for cocaine abuse2,11-14 because cocaine’s reinforcing and stimulant properties have long been associated with its propensity to bind to and inhibit monoamine transport systems, especially the DAT.15-24 Our work has concentrated on the design of compounds that inhibit all three monoamine uptake systems with different degrees of potency and selectivity. In the search for a new class of compounds that may provide a different access to agents that target the transport systems, our attention was drawn to bupropion (Figure 1), a compound marketed as an antidepressant (Wellbutrin) as well as a smokingcessation drug (Zyban). Bupropion is a 2-substituted aminopropiophenone25,26 that has been explored extensively. Interestingly, and of relevance to the work which we describe later, the enantiomers of bupropion may not differ in their ability to * To whom correspondence should be addressed. Tel: 1-781-932-4142. Fax: 1-781-933-6695. E-mail: [email protected]. † Organix Inc.. ‡ Naval Research Laboratory. § Harvard Medical School and New England Regional Primate Research Center.

Figure 1.

inhibit biogenic amines.27 Bupropion is structurally closely related to a 2-substituted aminopentanophenone, pyrovalerone (Figure 1). In 1992, Lancelot reported that pyrovalerone inhibits the DAT and the NET and is a weak inhibitor of the SERT.28 Its synthesis was first reported by Heffe in 1964.29 Stille30 and Holliday31 confirmed its stimulant activity in animals and humans in 1963. In 1971, pyrovalerone was demonstrated to reduce symptoms of chronic fatigue in humans.32 Later studies in rat hearts revealed that it inhibits NE uptake and effects the release of NE from storage or functional pools.25,33 In 1993, Vaugeois et al.34 reported that pyrovalerone stimulated the locomotor activity in mice (2 mg/kg) for up to 1 h and that this duration of action paralleled the time course of its DAT occupancy. Notwithstanding this early clinical interest, the literature reveals little SAR on pyrovalerone. Lancelot et al.28 reported the exchange of the phenyl ring for a thiophenyl ring. This exchange resulted in analogues of similar potency for both the inhibition of DA and NE uptake. Furthermore, an increase in size of the nitrogen containing ring from a five-membered pyrrolidine to a sixmembered piperidine caused a substantial loss in binding potency in all uptake mechanisms. These researchers also reported that their analogues inhibited both DA and NE uptakes but were less potent at inhibition of the SERT, a finding very similar to that now reported for the analogues of the present study. Since then, one pharmacological study has appeared34 in which pyrovalerone was shown to occupy striatal sites labeled with GBR12783 and manifest an increase in locomotor activity. However, there are no further reports concerning SAR or biological enantioselectivity of pyrovalerone or analogues. Consequently, there is little directly relevant SAR to guide the

10.1021/jm050797a CCC: $33.50 © 2006 American Chemical Society Published on Web 01/25/2006

A Promising Class of Monoamine Uptake Inhibitors

Journal of Medicinal Chemistry, 2006, Vol. 49, No. 4 1421

Scheme 1. General Heffe Synthesis of 1-(4-Substituted phenyl)-2-pyrrolidin-1-yl-pentan-1-ones 4a,b

a Reagents and conditions: (i) n-BuMgCl; (ii) H SO ; (iii) AlCl , Br ; (iv) pyrrolidine. b The Heffe synthesis was not followed for certain compounds. 2 4 3 2 Synthetic details for those compounds are presented in the Experimental Section and are discussed in the text.

Scheme 2. Synthesis of Analogues 6, 7, 9f, and 9ga

Scheme 3. Synthesis of Compounds 9a-e

a Reagents and conditions: (i) AlCl ,Br ; (ii) Li CO , LiBr, DMF; (iii) 3 2 2 3 pyrrolidine HCl, (HCHO)n; (iv) pyrrolidine; (v) n-BuNH2; (vi) piperidine.

selection of pyrovalerone analogues for evaluation as potential cocaine medication. Herein we describe the synthesis and biological evaluation of a family of analogues of 1-(4-methylphenyl)-2-pyrrolidin1-yl-pentan-1-one (pyrovalerone) 4a and show, in general, that these compounds are potent inhibitors of the dopamine transporter (DAT) and norepinephrine transporter (NET) but are relatively poor inhibitors of the serotonin transporter (SERT). In addition, certain compounds were evaluated for affinity at 5HT1A, 5HT1B, 5HT1C, D1, D2, and D3 receptors and were found to be inactive. Chemistry The general route of the synthesis of pyrovalerone and close analogues (Scheme 1) is straightforward and was first published by Heffe in 1964.29 We have adopted this route wherever possible. The synthesis of target compounds 4 is presented in Scheme 1. The synthesis of 6, 7, 9f, and 9g is shown in Scheme 2. The synthesis of compounds 9a-e is presented in Scheme 3. Ketones (Scheme 1) 2d-f are commercially available. Compound 2m was prepared from 2k. Ketones 2i-j and 2n were obtained from 2f, according to a literature procedure.35 Other required ketones 2 were obtained either from aryl nitriles 1 or by Friedel-Crafts acylation of suitably substituted aryl precursors. Thus, arylnitriles 1 were subjected to reaction with nBuMgCl, followed by acidic hydrolysis to afford ketones 2h, 2p, 2r-u, and 2w in excellent yields. Alternatively, ketones

2a, 2g, and 2o were prepared by Friedel-Crafts acylation of toluene, iodobenzene, and acetanilide, respectively, with valeroyl chloride. These ketones 2 were then brominated selectively with bromine in the presence of a catalytic amount of aluminum trichloride to provide R-bromoketones 3 quantitatively. Ring bromination did not occur under these conditions. The R-bromoketones were then used without further purification in the subsequent reactions with pyrrolidine at room temperature to provide 4a, d-j, m-p, r-u, and 4w. Compounds 4k and 4v were obtained by BBr3 demethylation of 4m and 4w, respectively. Sonogashira coupling of 4g with propyne was used to prepare compound 4q, and Stille coupling with the respective stannylated heterocycles was employed to prepare compounds 4x-z from 4f. Nitro compound 4l was obtained by the oxidation of compound 4o with H2O2/trifluoroacetic anhydride. The resolution of racemic 1-(4-methylphenyl)-2-pyrrolidin1-yl-pentan-1-one 4a was accomplished by recrystallization from CH2Cl2/hexane of the diastereomeric salts obtained upon reaction with dibenzoyl-D-tartaric acid in refluxing ethanol (Scheme 4). This provided the (2R)-pyrovalerone dibenzoyl-D-tartrate salt. The purity was determined by 1H NMR spectroscopy. The diastereomeric salt mixture showed two sets of triplets at δ ) 0.73 and 0.69 (CDCl3). These correspond to the ω-methyl protons of the pyrovalerone moieties of the (2S)-pyrovalerone

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Journal of Medicinal Chemistry, 2006, Vol. 49, No. 4

Scheme 4. Resolution of 1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one 4aa

a Reagents: (i) Dibenzoyl-D (or L)-tartaric acid, EtOH; (ii) recrystallization (CH2Cl2/hexanes); (iii) Na2CO3‚Et2O.

dibenzoyl-D-tartrate and (2R)-pyrovalerone dibenzoyl-D-tartrate salts, respectively. After four recrystallizations, the triplet at 0.73 ppm was no longer visible. The absence of the triplet attests to the diastereomeric purity of the compound, and this can be assumed to be >95% de on the basis of the limits of sensitivity of the NMR experiment. It is noteworthy that the purified dibenzoyl-D-tartaric and L-tartaric acid diastereomeric salts of 4b and 4c are enantiomers, and both resonate at δ 0.71 for ω-methyl. Assignment of the absolute optical configuration of this diastereomer was confirmed by X-ray structural analysis as (2R) (optical rotation was [R]20D +59.6° (c 1.06, EtOH)). Upon treatment with aqueous Na2CO3 and extraction into Et2O, then treatment with HCl, this diastereomeric salt gave (2R)pyrovalerone 4c. (2S)-Isomer 4b was then obtained from the enriched mother liquors by reaction with dibenzoyl-L-tartaric acid, recrystallization of the diastereomeric salts (optical rotation was [R]20D -61.1° (c 1.07, EtOH)), and liberation of 4b upon treatment with aqueous sodium carbonate. The chiral center does not epimerize under these conditions. The enantiomeric purity of 4b and 4c can be anticipated to be >95% ee, that is, the same as the diastereomeric purity of the precursor dibenzoyl tartrate salts. Enantiomeric purity was confirmed by HPLC chiral resolution using a Chiralpak AD column. Each isomer was thus confirmed to be >99% pure (ee > 98%). R,β-Unsaturated ketones 5a and 5b were obtained (Scheme 2) by dehydrobromination of 3a and 3u with Li2CO3/LiBr in DMF. Reaction with pyrrolidine then gave 6a and 6b respectively. Compounds 7a and 7b were accessible via the Mannich reaction of 3a and 3b with paraformaldehyde and pyrrolidine hydrochloride. Compound 3u was also used to provide 9f (reaction with butylamine) and 9g (reaction with piperidine). Compounds 9a and 9b were prepared (Scheme 3) by reaction of the appropriate R-bromoketones with pyrrolidine. Compounds 9c-e were prepared from 2-pyrrolidinyl 829 by alkylation with propargyl bromide in the presence of sodium amide or by alkylation with allyl bromide followed by treatment with aqueous sodium hydroxide. Reduction of 4a with LiAlH4 gave 9h and 9j as a mixture of diastereomers, which were separated by flash column chromatography. All amines were converted to their HCl salts and recrystallized from EtOH/Et2O for biological assay with the exception of 4v, which was isolated as its HBr salt. Biology The ligand affinities (Ki, nM) for inhibition of dopamine, serotonin, and norepinephrine transporters were determined in competition studies with [125I]RTI 55. Inhibition of monoamine uptake (IC50, nM) was evaluated in competition with [3H]dopamine, [3H]serotonin, and [3H]norepinephrine and is presented in Tables 1 and 2. In general, the analogues of 1-(4-

Meltzer et al.

methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one provide numerous examples of compounds that are potent inhibitors of the dopamine transporter and of dopamine reuptake. These compounds also inhibit NE reuptake with some potency but are generally inactive at the SERT and for serotonin reuptake inhibition. One notable exception to this selectivity is the naphthyl analogue 4t, which binds to all three transporters and inhibits reuptake at the nanomolar potency range. The lead compound, racemic pyrovalerone 4a, has been demonstrated here to be biologically enantioselective because the DAT inhibitory potency of the racemic mixture of 4a resides entirely with the 2S-enantiomer, 4b (DAT Ki ) 18.1 nM; DA IC50 ) 16.3 nM). Of these DAT/NET compounds, the most potent is 3,4-dichlorophenyl substituted 4u, with DAT Ki ) 11.5 nM and NET Ki ) 37.8 nM. At this time, it is unclear whether the inherent lipophilicity of both 4t and 4u is primarily responsible for their inhibitory potency. This question is currently being explored further. Discussion The lead compound for these studies was racemic 1-(4methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one (pyrovalerone) 4a (Table 1). In our assays, this compound proved a potent inhibitor of both RTI 55 binding (Ki ) 21.4 nM, about 20-fold more potent than cocaine, as measured in the same assay) and dopamine (DA) uptake (IC50 ) 52 nM, about 9-fold more potent than cocaine). Its potency of RTI 55 inhibition of the NET (Ki ) 195 nM) as well as norepinephrine (NE) uptake (IC50 ) 28.3 nM) was also marked. It was found to be more potent than cocaine in this assay by about 11-fold and 13-fold, respectively. The discrepancy between the inhibition of RTI 55 binding at the NET compared with the inhibition of NE uptake was seen throughout this series of compounds. This discrepancy was first reported by Eshleman et al. in 1999.36 They also noted that such differences were less evident in the case of DATs and SERTs. They suggested that this difference was likely a consequence of the ligand binding site on the NET being less closely linked to the sites of drug interactions with the substrate and (NE) translocation than is the case for the DAT and the SERT. Compound 4a was relatively inert at the SERT, with potency in the micromolar range. Therefore, racemic 4a was potent at the DAT and NET and selective against the SERT. Compound 4a exists as two enantiomers; only racemic 4a has been evaluated previously. The critical importance of absolute stereochemistry on biological function is well established. It is particularly relevant that both amphetamine (1-phenyl-2-aminopropane) and cathinone (1-phenyl-2-aminopropane-1-one) are biologically enantioselective with respect to their inhibition of DATs and NETs.37,38 Indeed, the S-enantiomers are the eutomers in both cases. These two compounds bear strong structural similarities to the 1-aryl-2-pyrrolidin-1-yl-pentan-1-one analogues of this study, and therefore it was likely that their binding to, and thus inhibition of, these transporters may likewise be similar. However, the structural similarity of the 1-aryl-2pyrrolidin-1-yl-pentan-1-ones to the 2β-carbomethoxy-3R-aryl8-azabicyclo[3.2.1]octane (tropane) class of DAT inhibitors is less clear. It is therefore interesting to note a comparison that utilized Dreiding models of WIN 35,428 (Figure 1) with enantiomers 2S-4b and 2R-4c (Scheme 4). The pyrrolidine nitrogens and the centroids of the aromatic rings were held coincident. In this rudimentary analysis, the propyl side chain in the 2S configuration overlapped with the C2-β-carbomethoxy of the tropane. However, the 2R-configured compound had the propyl chain in a position similar to that of the 2R-carbomethoxy



Table 1. Affinity of 4 ([125I]RTI 55) and Its Inhibition of Uptake of [3H]dopamine, [3H]serotonin, and [3H]norepinephrine by HEK-hDAT, HEK-hSERT, and HEK-hNET Cellsa

R

DAT Ki (nM)

D uptake (IC50)

DRb

cocaine 4-CH3 (R/S) 4-CH3 (S) 4-CH3 (R) H 4-F 4-Br 4-I 3-I 4-CN 4-CH2OH 4-OH 4-NO2 4-OCH3 4-CO2CH3 4-NHCOCH3 4-CF3 4-CtCCH3 2-CH3 3-CH3 naphthyl 3,4-Cl2 3,4-(OH)2 3,4-(OCH3) 2 4-furan 4-thiophene 4-mepyrrole

432 ( 29 21.4 ( 4.6 18.1 ( 3.0 1330 ( 300 33.7 ( 5.4 82.0 ( 25 51.0 ( 6.7 81.4 ( 9.2 109 ( 32 5900 ( 1100 48.7 ( 2.2 125 ( 23 266 ( 32 329 ( 33 360 ( 140 30.2 ( 2.0 >10 µM 61.0 ( 16 59.7 ( 9.0 51.0 ( 14 20.1 ( 7.1 11.5 ( 1.4 84.0 ( 12 >10 µM 105 ( 17 460 ( 120 3850 ( 330

461 ( 46 52.0 ( 20 16.3 ( 2.3 1790 ( 320 52.3 ( 6.2 185 ( 62 39.5 ( 7.5 32.0 ( 11 52.0 ( 16 1000 ( 170 44.3 ( 8.4 49.7 ( 3.4 1110 ( 340 283 ( 66 154 ( 50 67.9 ( 8.4

1.06 2.43 0.91 1.35 1.55 2.26 0.77 0.39 0.48 0.17 0.91 0.40 4.17 0.86 0.43 2.25

11.8 ( 2.8 63.0 ( 19 62.9 ( 6.9 40.0 ( 13 43.0 ( 20 42.0 ( 11

0.19 1.06 1.23 1.99 3.91 0.50

122 ( 18 539 ( 69 5400 ( 1600

1.16 1.17 1.40

cpd 4 a b c d e f g h i j k l m n o p q r s t u v w x y z

O-2371 O-2442 O-2440 O-2387 O-2370 O-2419 O-2493 O-2495 O-2575 O-2577 O-2418 O-2443 O-2417 O-2558 O-2439 O-2481 O-2537 O-2479 O-2480 O-2482 O-2390 O-2574 O-2512 O-2441 O-2438 O-2446

SERT Ki (nM)

SER uptake (IC50)

NET Ki (nM)

NE uptake (IC50)

358 ( 24 3770 ( 560 2220 ( 550 >10 µM >10 µM >10 µM 830 ( 190 301 ( 26 1400 ( 120 >10 µM >10 µM >10 µM 2460 ( 290 4080 ( 410 3950 ( 690 >10 µM 959 ( 92 6700 ( 1100 3720 ( 520 5900 ( 1600 33.1 ( 1.1 199 ( 50 >10 µM 7460 ( 770 3330 ( 1200 3320 ( 280 >10 µM

494 ( 51 2780 ( 590 1070 ( 230

2150 ( 190 195 ( 26 109 ( 45 >10 µM 199 ( 45 830(140 386 ( 53 310 ( 34 670 ( 130 >10 µM 150 ( 23 1290 ( 480 2690 ( 530 2600 ( 1000 1140 ( 320 4000 ( 1100 >10 µM 69.8 ( 5.4 425 ( 63 216 ( 38 136 ( 27 37.8 ( 3.2 219 ( 71 >10 µM 95 ( 20 370 ( 160 >10 µM

378 ( 48 28.3 ( 8.1 11.3 ( 2.4

1050 ( 90 197 ( 35 1070 ( 170

1110 ( 450 2430 ( 720 2350 ( 560 1030 ( 340 3300 ( 1100 2020 ( 670 4400 ( 1100 46.0 ( 5.5 600 ( 63 1540 ( 220 2180 ( 440 1960 ( 720

56.0 ( 13 171 ( 35 83.0 ( 30 46.5 ( 8.4 81.0 ( 20 12.4 ( 2.8 86.7 ( 7.5 531 ( 67 235 ( 8.7 22.8 ( 3.3 317 ( 64 19.3 ( 4.1 19.7 ( 3.3 9.4 ( 0.8 11.7 ( 0.9 21.0 ( 0.6 7.6 ( 2.9 93 ( 38 263 ( 94

a Numbers represent the means ( SEM from at least three independent experiments, each conducted with duplicate (for binding assays) or triplicate (for uptake assays) determinations. When the Ki or the IC50 values for the test compound is greater than 10 µM, only two experiments were conducted, and no standard error was reported. Data from Oregon Health and Science University and VA Medical Center, Portland, OR. b DR ) discrimination ratio.

Table 2. Affinity of 6, 7, and 9 ([125I]RTI 55) and Their Inhibition of the Uptake of [3H]dopamine, [3H]serotonin, and [3H]norepinephrine by HEK-hDAT, HEK-hSERT, and HEK-hNET Cellsa

cpd 6a 6b 7a 7b 9a 9b 9c 9d 9e 9f 9g 9hb 9jb

R1 O-2525 O-2524 O-2477 O-2478 O-2384 O-2494 O-2556 O-2557 O-2576 O-2389 O-2388 O-2529-1 O-2529-2

4-CH3 3,4-Cl2 4-CH3 3,4-Cl2 3,4-Cl2 4-CH3 4-CH3 3,4-Cl2 4-CH3

R2

CH2CH3 CH2CH(CH3)2 CH2CHdCH2 CH2CHdCH2 CH2CtCH

DAT Ki (nM) >10 µM 8440 ( 310 >10 µM 1530 ( 520 28.8 ( 2.1 13.7 ( 3.0 90.5 ( 3.1 39.9 ( 5.5 2310 ( 110 520 ( 110 144 ( 48 >10 µM >10 µM

DA uptake (IC50) >10 µM 2900 ( 1300 55.0 ( 12 5.9 ( 2.3 55 ( 17 18.3 ( 3.7 231 ( 25 1190 ( 58 666 ( 89

SERT Ki (nM) >10 µM 3900 ( 1000 4100 ( 1800 630 ( 110 810 ( 150 2870 ( 10 >10 µM 1060 ( 170 >10 µM 5080 ( 60 2460 ( 260 >10 µM >10 µM

SER uptake (IC50) 1780 ( 220 4800 ( 1200 710 ( 170 441 ( 12 2040 ( 150 440 ( 170 >10,000 >10,000

NET Ki (nM) >10 µM >10 µM >10 µM >10 µM 262 ( 36 259 ( 80 1400 ( 370 509 ( 100 4100 ( 1300 4200 ( 1200 2350 ( 230 >10 µM >10 µM

NE uptake (IC50)

18.5 ( 8.0 18.0 ( 5.0 88.0 ( 16 24.9 ( 8.2 350 ( 120 2520 ( 190 800 ( 200

a Numbers represent the means ( SEM from at least three independent experiments, each conducted with duplicate (for binding assays) or triplicate (for uptake assays) determinations. When the Ki or the IC50 values for the test compound is greater than 10 µM, only two experiments were conducted, and no standard error was reported. Data from Oregon Health and Science University and VA Medical Center, Portland, OR. b Compounds 9h and 9j are pure diastereomers.

of the tropane. It has been well established that the 2Rcarbomethoxy tropane analogues are less potent at the DAT than their 2β-carbomethoxy counterparts. On this basis, we had

postulated that 2S-4b might be the active enantiomer at the DAT. As shown in Table 1, enantiopure (2R-4c) is a poor inhibitor of RTI 55 binding at both DAT (Ki ) 1330 nM) and SERT (Ki

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> 10 µM). In contrast, enantiopure (2S-4b) was quite potent at DAT (Ki ) 18.1 nM) and selective (SERT: Ki > 2 µM). It was interesting that this relative potency of the 2S-4b enantiomer extended to the NET. Here, the 2R-4c enantiomer was effectively inert at NET inhibition and NE uptake, and the potency of racemic 4a resided exclusively in the 2S-4b enantiomer (NET: Ki ) 109 nM; NE uptake: IC50 ) 11.3 nM). It is evident from the biological data (Table 1) that the inhibitory activities of these compounds cannot be easily correlated with varying electron density on the aromatic ring, with lipophilicity, or molecular refractivity. To this extent, this family of 1-aryl-2-pyrrolidin-1-yl-pentan-1-one analogues differs from other monoamine uptake inhibitors, such as the 8-oxa-, 8-thia-, and 8-aza-bicyclo[3.2.1]octanes11,12,39,40 and methylphenidate analogues,41,42 where structure-activity relationships (SAR) are more easily discerned. Notwithstanding, certain relationships were evident among these analogues. Most clear was the fact that these 1-aryl-2-pyrrolidin-1-yl-pentan-1-one analogues were generally poor inhibitors of the SERT. Only two compounds (4t and 4u) manifested SERT Ki values of 5, and therefore none can be regarded as cocaine antagonists. Their use as potential medications for cocaine addiction may be derived from the onset and duration of action extensions, and these factors are currently under investigation. Of note, the biaryl compounds 4x-z lacked impressive potency at all sites. This, again, is contrary to the effects of such substitution in the bicyclo[3.2.1]octane series in both the 8-aza47 and 8-oxa series, as we shall report elsewhere.48 Table 2 presents an array of compounds that explored the displacement of the pyrrolidine ring along the butyl chain (6a, b), the introduction of different C2 side chains (9a,b) as well as the introduction of side chain unsaturation (9c-e), and the effects of opening the pyrrolidine ring (9f) as well as expanding it to the six-membered piperidine (9g). Finally, the reduction of the ketone to obtain both isomers (9h and 9j) is presented. The stereochemistry of these two diastereomers has not been determined yet. However, neither isomer shows any potency at the DAT, SERT, and NET. A comparison of 6a with 4a and 6b with 4u showed that essentially all inhibitory potency at all three transporters was lost when the pyrrolidine ring was moved one carbon along the chain. The nature of the pyrrolidine itself appears to be important because when it was opened (9f) or expanded (9g), the inhibitory potency was much reduced compared with that of parent compound 4u. Lancelot et al.28 had published a similar finding in their evaluation of 2-amino1-(2-thienyl)-1-pentanones. Reduction of the ketone 4a to yield the diastereomeric alcohols 9h and 9j provided totally inactive compounds. Modification of the alkyl chain of 4a proved interesting. Although a terminal acetylene (9e) resulted in a substantial loss of potency at DATs, SERTs, and NETs, the allyl compounds 9c and 9d retained potency at DATs. 3,4Dichloro compound 9d (DAT: Ki ) 39.9 nM) was again the more potent of the two, although NET potency declined substantially (Ki ) 509 nM) compared with that of comparative compound 4u (Ki ) 37.8 nM). Of these chain altered compounds, isobutyl analogue 9b proved most interesting with DAT Ki ) 13.7 nM but DA uptake IC50 ) 5.9 nM. This compares with data for 4a (DAT Ki ) 21.4 and DA uptake IC50 ) 52 nM). Thus, the introduction of a branching methyl in the side chain has served to increase DA inhibition about 10-fold over the parent compound 4a. The possible significance of this is not clear at this time. The biological selectivity within this class of compounds proved striking. Thirteen compounds (4b, f, k-m, o, p, r-t,


y, 6a, and 6b) were evaluated for inhibition of 5HT1A, 5HT1B, 5HT1C, D1, D2, and D3 receptors. The compounds were essentially inactive (IC50 > 10 µM) in these assays. Two compounds (4o, which was a selective DAT inhibitor and 4t, which had similar potency at the DAT and SERT) were selected for evaluation of locomotor activity. Both manifested a timeand dose-dependent stimulation of locomotor activity (ED50 ) 0.21 mg/kg and 2.2 mg/kg, respectively) with a duration of action of >8 h. Conclusion A family of 38 analogues of lead compound 1-(4-methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one (pyrovalerone) has been prepared. The biological activity at dopamine, serotonin, and norepinephrine transporters has been determined. This family has yielded compounds that provide selective inhibitors of the dopamine and norepinephrine transporters with little effect upon serotonin trafficking. Furthermore, a subset of compounds selected for evaluation of their effect upon serotonin and dopamine receptors has shown them to be inactive at these sites. Lead compound 4a has been demonstrated to be biologically enantioselective, and it remains to be determined whether this enantioselectivity extends to other members of this family of compounds. Two compounds, 4o and 4t, manifested a timeand dose-dependent stimulation of locomotor activity with a duration of action of >8 h. The inhibitory potency, the neurotransmitter selectivity profile, and the inactivity at selected receptor sites of 4k and 4o have encouraged us to enter behavioral pharmacological evaluation in rat drug discrimination studies, and in vivo studies are currently ongoing. Experimental Section NMR spectra were recorded on a JEOL 300 NMR spectrometer (300.53 MHz for 1H and 75.58 MHz for 13C) with tetramethylsilane (TMS) as the internal standard and DMSO-d6 as the solvent, with the exception of compounds 2 and 3, which were measured in CDCl3. Optical rotations were measured on a Jasco P1010 polarimeter at room temperature. HPLC and MS data were obtained on an Agilent series 1100 LC/MSD system. Melting points are uncorrected and were measured on a Mel-Temp melting-point apparatus. Thin-layer chromatography (TLC) was carried out on Baker Si 250F plates. Visualization was accomplished with iodine vapor, UV exposure, and treatment with phosphomolybdic acid (PMA). Flash chromatography was carried out on Baker silica gel 40 µM (silica gel). All reactions were conducted under an atmosphere of dry nitrogen. Elemental analyses were performed by Atlantic Microlab, Norcross, GA. Chemicals obtained from commercial sources were used as received. Room temperature is 22 ( 2 °C. Yields have not been optimized. General Procedure A. Preparation of Intermediate Ketones 2. Ketones 2 were prepared (except where noted) by the alkylation of the analogous commercially available nitrile compounds, followed by acidic hydrolysis. The nitrile (10 mmol) was added in several portions, over 0.5 h, to a solution of the n-BuMgCl (12 mmol) in toluene (20 mL). The reactions were monitored by TLC and heated where necessary. Generally, after 2 h of stirring at room temperature, the reaction was complete. The reaction mixture was poured onto ice, and concentrated H2SO4 (2 mL) was added. Hydrolysis of the intermediate imine usually occurred at room temperature after several minutes. However, for some substrates, heating was necessary to effect this transformation. The organics were extracted into Et2O, dried (MgSO4), filtered, and reduced in vacuo to an oil. General Procedure B. Preparation of Intermediate r-Bromoketones 3. Compounds 3 were prepared by the R-bromination of ketones 2. The ketone (as a solution in Et2O, or CH2Cl2 (for


less soluble substrates)) was cooled in an ice bath, and anhydrous AlCl3 was added to the solution (1-5 mol %). Bromine (approximately 0.1 mol equiv) was added to the solution all at once. Typically, after 10 min the solution changed from light orange to colorless. (If this change did not occur at 0 °C, then the mixture was warmed to room temperature.) The remaining bromine (0.9 mol equiv) was then added to the solution in a dropwise manner over 5 min. The solution was neutralized (aqueous NaHCO3), separated, dried (MgSO4), filtered, and reduced to a light-colored oil in vacuo. Yields were quantitative, and the crude materials were sufficiently pure (1H NMR) for use in the subsequent step. General Procedure C. 1-Aryl-2-pyrrolidin-1-yl-pentan-1-ones (4). Compounds 4 were prepared employing general procedure C except where noted. R-Bromoketone 3 (10 mmol) was dissolved in Et2O (10 mL) (EtOH is a suitable alternative solvent) and cooled in an ice bath. Pyrrolidine (22 mmol) was added all at once. The mixture became orange, and an oil was observed to separate from the solution. After 1-24 h of stirring at room temperature, the crude reaction mixture was partitioned between H2O (10 mL) and Et2O. The Et2O layer was separated, and the aqueous layer was washed with Et2O (2 × 10 mL). The ether layer was extracted with 1 M aqueous HCl (2 × 10 mL) and then back-extracted into Et2O (3 × 10 mL) by basification to pH 8-9 with 20% aqueous Na2CO3 or 2 M aqueous NaOH. The Et2O extracts were dried (MgSO4) and filtered. The filtrate was treated with 2 M ethereal HCl (usually 5-10 mL) until the precipitation of solid or oil ceased. Solids (oils were triturated to give solids) were collected by filtration and recrystallized from EtOH/Et2O. 1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4a). 1-(4-Methylphenyl)pentan-1-one (2a) was prepared by Friedel-Crafts acylation of toluene: 1H NMR δ 7.86 (dd, 2H), 7.25 (dd, 2H), 2.92 (m, 2H), 2.41 (s, 3H), 1.71 (m, 2H), 1.40 (m, 2H), 0.95 (t, 3H) was brominated (general procedure B) to provide 2-bromo-1-(4-methylphenyl)-pentan-1-one 3a. 1H NMR δ 7.92 (d, 2H), 7.29 (d, 2H), 5.14 (dd, 1H), 2.43 (s, 3H), 2.25-2.05 (m, 2H), 1.65-1.35 (m, 2H), 0.98 (t, 3H). Compound 4a, obtained as a colorless solid, was prepared from 3a (general procedure C): yield 68%; mp 180 °C dec. 1H NMR δ 10.8-10.65 (br, 1H), 8.01 (d, 2H), 7.44 (d, 2H), 5.56 (m, 1H), 3.7-3.55 (br, 1H), 3.55-3.4 (br, m, 1H), 3.35-3.2 (br, m, 1H), 3.15-3.0 (br, m, 1H), 2.42 (s, 3H), 2.15-1.85 (br, m, 6H), 1.4-1.2 (m, 1H), 1.15-0.95 (m, 1H), 0.78 (t, 3H); 13C NMR δ 196.1, 145.8, 132.1, 129.8, 129.0, 67.1, 53.5, 51.9, 31.8, 22.9, 21.3, 17.4, 13.7; APCI MS m/z: 246 (M + 1). Anal. (C16H24ClNO‚1/6H2O) C, H, N, Cl. (1R)-1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4c) and (1S)-1-(4-Methylphenyl)-2-pyrrolidin-1yl-pentan-1-one Hydrochloride (4b). 1-(4-Methylphenyl)-2pyrrolidin-1-yl-pentan-1-one hydrochloride 4a (10.0 g, 35.5 mmol) was extracted into Et2O from 20% aqueous Na2CO3 at pH 8-9. The ether was removed, and the free base was dissolved in EtOH (50 mL) and heated to 70 °C. Dibenzoyl-D-tartaric acid (12.7 g, 35.5 mmol) in hot ethanol (150 mL) was added all at once to the pale-yellow solution of the free base. The resulting colorless solution was refluxed for 1 min and cooled, and the solvent was removed in vacuo. The residue was dissolved in CH2Cl2 (530 mL), and hexane (700 mL) was added with swirling. After 3 days, the resulting crystalline solid (9.1 g) was collected by filtration. 1H NMR (CDCl3) showed a diastereomeric excess (de) of 70-75%. Three consecutive recrystallizations from CH2Cl2/hexane (300/400 mL) gave a single diastereoisomer (6.1 g, 61%); mp 100-120 °C. 1H NMR δ 8.10 (d, 4H), 7.87 (d, 2H), 7.51 (t, 2H), 7.37 (t, 4H), 7.18 (d, 2H), 5.91 (s, 2H), 5.37 (t, 1H), 3.75 (br, m, 2H), 2.32 (s, 3H), 2.0-1.8 (br, m, 6H), 1.4-1.1 (br, m, 4H), 0.71 (t, 3H). X-ray structural analysis of this compound showed it to be the dibenzoylD-tartaric acid salt of (1R)-1-(4-methylphenyl)-2-pyrrolidin-1-ylpentan-1-one. [R]20D +59.6° (c 1.06, EtOH). The salt was dissolved in 20% aqueous Na2CO3 and extracted into Et2O. The Et2O layer was collected, dried, and filtered. Ethereal 2 M HCl was added to this solution to provide a white solid that was recrystallized from EtOH/Et2O to give pure (1R)-1-(4-methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one hydrochloride (4c). The

1426


physical properties of this compound were identical to those of the racemic material 4a. The residues from the recrystallization of the dibenzoyl-D-tartaric acid (1R)-1-(4-methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one were combined, and the free base was liberated with 20% aqueous Na2CO3. The ethereal extracts were washed once with 20% aqueous Na2CO3, dried (MgSO4), filtered, and reduced in vacuo to an oil (5.2 g, 21 mmol). This oil was dissolved in hot EtOH (50 mL), and a solution of dibenzoyl-L-tartaric acid (7.5 g, 21 mmol) in hot EtOH (100 mL) was added with swirling. The mixture was refluxed for 1 min and cooled, and the solvent was removed in vacuo. Four recrystallizations, as described above, gave a single diastereoisomer (5.4 g, 50%). X-ray structural analysis confirmed the diastereomeric salt of dibenzoyl-L-tartaric acid (1S)-1-(4-methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one. [R]20D -61.1° (c 1.07, EtOH). The hydrochloride salt of (1S)-1-(4-methylphenyl)-2-pyrrolidin1-yl-pentan-1-one 4b was then prepared as described above for (1R)1-(4-methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one. The enantiomeric purities of 4b and 4c were confirmed by chiral HPLC (Chiralpak AD, 0.46 × 25 cm (I.D. × L); flow rate 1 mL/ min; eluent 2-10% EtOH/hexanes + 0.1% NEt3). 4b: tR ) 6.77 min, purity 99.8%; 4c: tR ) 5.85 min, purity 100%. Single-Crystal X-ray Analysis of Dibenzoyl-D-tartaric Acid Salt of (1R)-1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one. Monoclinic crystals of the purified title compound were obtained from CH2Cl2/hexane. A representative crystal was selected, and a 1.54178 Å data set was collected at 198 K. Pertinent crystal, data collection, and refinement parameters are the following: crystal size, 0.32 × 0.12 × 0.03 mm3; cell dimensions, a ) 7.8458 (10) Å, b ) 13.4366 (2) Å, c ) 18.2054 (3) Å, R ) 90°, β ) 93.717 (10)°, γ ) 90°; formula, C40H51NO9; formula weight ) 689.82; volume ) 1915.19 (5) Å3; calculated density ) 1.196 g cm-3; space group ) P21; number of reflections ) 11 525, of which 5630 were considered to be independent (R int ) 0.0244). The refinement method was full-matrix least squares on F2. The final R indices were [I > 2σ (I)] R1 ) 0.0520 and wR2 ) 0.1439. Single-Crystal X-ray Analysis of Dibenzoyl-L-tartaric Acid (1S)-1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one. Monoclinic crystals of the purified dibenzoyl-L-tartaric acid (1S)-1-(4methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one were obtained from CH2Cl2/hexane. A representative crystal was selected, and a 1.54178 Å data set was collected at 153 °K. Pertinent crystal, data collection, and refinement parameters are the following: crystal size, 0.58 × 0.16 × 0.05 mm3; cell dimensions, a ) 7.8456 (1) Å, b ) 13.4605 (2) Å, c ) 18.2956 (3) Å, R ) 90°, β ) 93.5910 (10)°, γ ) 90°; formula, C40H51NO9; formula weight ) 689.82; volume ) 1930.88 (5) Å3; calculated density ) 1.186 g cm-3; space group ) P21; number of reflections ) 9774, of which 5860 were considered to be independent (Rint ) 0.0317). The refinement method was fullmatrix least squares on F2. The final R indices were [I > 2σ (I)] R1 ) 0.0537 and wR2 ) 0.1410. 2-Pyrrolidin-1-yl-1-phenylpentan-1-one (4d). Commercially available 2d was brominated (general procedure B) to give 2-bromo1-phenylpentan-1-one 3d. 1H NMR δ 8.02 (d, 2H), 7.62 (m, 1H), 7.49 (t, 2H), 5.15 (dd, 1H), 2.25-2.05 (m, 2H), 1.7-1.4 (m, 2H), 0.99 (t, 3H). Compound 4d, obtained as a colorless solid, was prepared from 3d (general procedure C) (51% yield); mp 173 °C. 1H NMR δ 10.9-10.6 (br, 1H), 8.11 (d, 2H), 7.78 (t, 1H), 7.64 (t, 2H), 5.62 (m, 1H), 3.64 (br, m, 1H), 3.49 (br, m, 1H), 3.26 (br, m, 1H), 3.10 (br, m, 1H), 2.15-1.85 (m, 6H), 1.4-1.2 (m, 1H), 1.20.95 (m, 1H), 0.78 (t, 3H); 13C NMR 196.7, 134.9, 134.5, 129.2, 128.8, 67.3, 53.6, 51.9, 31.7, 22.9, 17.4, 13.7; APCI MS m/z: 232 (M + 1). Anal. (C15H22ClNO) C, H, N, Cl. 1-(4-Fluorophenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4e). Commercially available 2e was brominated (general procedure B) to give 2-bromo-1-(4-fluorophenyl)pentan-1-one 3e. 1H NMR δ 8.05 (dd, 2H), 7.16 (dd, 2H), 5.09 (dd, 1H), 2.25-2.05 (m, 2H), 1.7-1.35 (m, 2H), 0.99 (t, 3H). Compound 4e, obtained as a colorless solid, was prepared from 3e (general procedure C) (84% yield); mp 218 °C dec. 1H NMR δ 10.7-10.5 (br, 1H), 8.19 (m, 2H), 7.49 (t, 2H), 5.6-5.5 (br, m, 1H), 3.7-3.55 (br, 1H),

Meltzer et al.

3.55-3.4 (br, 1H), 3.3-3.15 (br, m, 1H), 3.15-3.0 (br, 1H), 2.151.8 (br, m, 6H), 1.35-1.15 (m, 1H), 1.15-0.95 (m, 1H), 0.79 (t, 3H); 13C NMR δ 195.2, 132.2, 132.0, 131.3, 116.6, 116.3, 67.2, 53.5, 51.9, 31.7, 22.9, 17.4, 13.7; APCI MS m/z: 250 (M + 1). Anal. (C15H21ClFNO) C, H, N, Cl. 1-(4-Bromophenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4f). Commercially available 2f was brominated (general procedure B) to give 2-bromo-1-(4-bromophenyl)pentan-1-one (3f). 1H NMR δ 7.88 (d, 2H), 7.63 (d, 2H), 5.06 (dd, 1H), 2.25-2.05 (m, 2H), 1.65-1.35 (m, 2H), 0.99 (t, 3H). Compound 4f, obtained as a colorless solid, was prepared from 3f (general procedure C) (62% yield); mp 200 °C dec. 1H NMR δ 10.7-10.5 (br, 1H), 8.03 (d, 2H), 7.87 (d, 2H), 5.56 (m, 1H), 3.7-3.55 (br, m, 1H), 3.553.4 (br, m, 1H), 3.35-3.1 (br, m, 1H), 3.1-3.0 (br, m, 1H), 2.11.8 (br, m, 6H), 1.4-1.2 (m, 1H), 1.15-0.95 (m, 1H), 0.78 (t, 3H); 13C NMR δ 196.0, 133.4, 132.4, 130.8, 129.4, 67.4, 53.7, 51.9, 31.6, 22.9, 17.3, 13.7; APCI MS m/z: 312, 310 (M + 1). Anal. (C15H21BrClNO) C, H, N, Cl. 1-(4-Iodophenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4g). 1-(4-Iodophenyl)pentan-1-one (2g) prepared by FriedelCrafts acylation of 4-iodobenzene and purified by distillation (bp 112 °C, 0.1 mmHg) and recrystallization from EtOH: (11% yield); 1H NMR δ 7.82 (d, 2H), 7.67 (d, 2H), 2.92 (t, 2H), 1.71 (m, 2H), 1.40 (m, 2H), 0.95 (t, 3H) was brominated (general procedure B) to give 2-bromo-1-(4-iodophenyl)pentan-1-one (3g). 1H NMR δ 7.85 (d, 2H), 7.72 (d, 2H), 5.06 (dd, 1H), 2.25-2.05 (m, 2H), 1.651.35 (m, 2H), 0.98 (t, 3H). Compound 4g was prepared from 3g (general procedure C) (37% yield); mp 218 °C dec. 1H NMR δ 10.75-10.65 (br, 1H), 8.05 (d, 2H), 7.84 (d, 2H), 5.53 (m, 1H), 3.7-3.65 (br, 1H), 3.65-3.5 (br, m, 1H), 3.3-3.15 (br, m, 1H), 3.15-3.0 (br, m, 1H), 2.1-1.8 (br, m, 6H), 1.35-1.15 (m, 1H), 1.15-0.95 (m, 1H), 0.78 (t, 3H); 13C NMR δ 196.3, 138.2, 133.6, 130.3, 104.6, 67.3, 53.7, 51.9, 31.6, 22.9, 17.3, 13.7; APCI MS m/z: 358 (M + 1). Anal. (C15H21ClINO) C, H, N, Cl. 1-(3-Iodophenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4h). 1-(3-Iodophenyl)pentan-1-one (2h) prepared in 29% yield from 3-iodobenzonitrile (general procedure A) and purified by column chromatography (3% EtOAc/hexane): Rf 0.25 (5% EtOAc/ hexane); 1H NMR δ 8.28 (t, 1H), 7.90 (m, 2H), 7.21 (t, 1H), 2.93 (t, 2H), 1.71 (m, 2H), 1.40 (m, 2H), 0.96 (t, 3H); 13C NMR δ 199.1, 141.6, 138.8, 137.0, 130.3, 127.1, 94.4, 38.3, 26.2, 22.4, 13.9, was brominated (general procedure B) to provide 2-bromo-1-(3-iodophenyl)pentan-1-one (3h). 1H NMR δ 8.33 (dd. 1H), 7.96 (ddd, 1H), 7.93 (ddd, 1H), 7.22 (d, 1H), 5.05 (dd, 1H), 2.25-2.05 (m, 2H), 1.7-1.35 (m, 2H), 0.98 (t, 3H). Compound 4h, obtained as a colorless solid, was prepared from 3h (general procedure C) (20% yield); mp 203 °C dec. 1H NMR δ 10.6-10.4 (br, 1H), 8.39 (s, 1H), 8.14 (d, 1H), 8.07 (d, 1H), 7.44 (t, 1H), 5.51 (m, 1H), 3.73.55 (br, m, 1H), 3.55-3.4 (br, m, 1H), 3.3-3.15 (br, m, 1H), 3.15-3.0 (br, m, 1H), 2.1-1.8 (br, m, 6H), 1.35-1.15 (m, 1H), 1.1-0.9 (m, 1H), 0.79 (t, 3H); 13C NMR δ 195.7, 143.3, 136.9, 136.1, 131.8, 131.3, 128.0, 95.7, 67.5, 53.8, 51.9, 31.5, 22.8, 17.2, 13.6; APCI MS m/z: 358 (M + 1). Anal. (C15H21ClINO) C, H, N, Cl. 4-(2-Pyrrolidin-1-yl-pentanoyl)benzonitrile Hydrochloride (4i). 4-(2-Bromopentanoyl)benzonitrile (3i): 1H NMR δ 8.11 (d, 2H), 7.80 (d, 2H), 5.07 (dd, 1H), 2.25-2.05 (m, 2H), 1.7-1.35 (m, 2H), 1.00 (t, 3H) was prepared (general procedure B) from 4-cyanovalerophenone (2i)35 and converted to 4i as described in general procedure C (70% yield); mp 197-199 °C dec. 1H NMR δ 10.910.7 (br, 1H), 8.24 (d, 2H), 8.14 (d, 2H), 5.7-5.55 (br, m, 1H), 3.7-3.6 (br, m, 1H), 3.6-3.5 (br, m, 1H), 3.3-3.1 (br, m, 2H), 2.1-1.8 (m, 6H), 1.4-1.2 (m, 1H), 1.1-0.9 (m, 1H), 0.77 (t, 3H); 13C NMR δ 196.2, 137.5, 133.2, 129.4, 117.9, 116.6, 67.8, 53.7, 51.9, 31.3, 22.9, 17.2, 13.7; APCI MS m/z: 257 (M + 1). Anal. (C16H21ClN2O‚1/4H2O) C, H, N, Cl. 1-(4-Hydroxymethylphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4j). 2-Bromo-1-(4-hydroxymethylphenyl)-pentan-1one (3j): 1H NMR δ 8.01 (d, 2H), 7.48 (d, 2H), 5.15 (dd, 1H), 4.79 (br, d, 2H), 2.25-2.05 (m, 2H), 2.05-1.95 (br, 1H), 1.651.4 (m, 2H), 0.99 (t, 3H) was prepared (general procedure B) from


1-(4-hydroxymethylphenyl)pentan-1-one (2j)35 and converted to 4j as described in general procedure C (79% yield); mp 186-187 °C dec. 1H NMR δ 10.6-10.4 (br, 1H), 8.05 (d, 2H), 7.56 (d, 2H), 5.7-5.4 (br, m, 2H), 4.62 (s, 2H), 3.7-3.55 (m, 1H), 3.55-3.3 (m, 1H), 3.35-3.15 (m, 1H), 3.1-3.0 (m, 1H), 2.1-1.8 (m, 6H), 1.3-1.15 (m, 1H), 1.15-0.95 (m, 1H), 0.78 (t, 3H); 13C NMR δ 196.2, 150.4, 132.8, 128.8, 126.7, 67.4, 62.2, 53.8, 51.9, 31.8, 22.8, 17.3, 13.7; APCI MS m/z: 262 (M + 1). Anal. (C16H24ClNO2‚1/ 4H2O) C, H, N, Cl. 1-(4-Hydroxyphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4k). 1-(4-Methoxyphenyl)-2-pyrrolidin-1-yl-pentan-1-one (4m) (9.00 g, 30.3 mmol) was freed from its hydrochloride salt by basification to pH 8-9 with 20% aqueous Na2CO3 and extraction into CH2Cl2. The free base was dissolved in CH2Cl2 (50 mL) and cooled to -78 °C. BBr3 (90 mL, 1.0 M solution in CH2Cl2, 90 mmol) was added to the solution over 0.5 h. The mixture was stirred for another hour before warming gradually to room temperature. The gummy mixture, which became difficult to stir, was quenched after 2 h with saturated aqueous NaHCO3, and the neutral organics were extracted into CH2Cl2. A white solid precipitated from the aqueous layer and was collected on a frit (2.8 g). This material was dissolved in Et2O and treated with 2 M ethereal HCl. The solid obtained was collected by filtration and then recrystallized from ethanol to give pure 1-(4-hydroxyphenyl)-2-pyrrolidin-1-yl-pentan1-one as its hydrochloride (4k) (2.9 g, 34%); mp 235 °C dec. 1H NMR (CD3OD) δ 7.99 (d, 2H), 6.93 (d, 2H), 5.26 (t, J ) 5.5 Hz, 1H), 3.7-3.0 (br, 4H), 2.2-1.9 (br, m, 6H), 1.4-1.1 (m, 2H), 0.89 (t, 3H); 13C NMR δ 195.0, 156.8, 132.9, 127.3, 117.0, 69.8, 33.9, 24.1, 18.6, 14.2; APCI MS m/z: 248 (M + 1). Anal. (C15H22ClNO2) C, H, N, Cl. 1-(4-Nitrophenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4l). A 50% w/w aqueous solution of H2O2 (7 mL, 0.12 mol) was added to CH2Cl2 (50 mL) that had been cooled in an ice bath. Trifluoroacetic anhydride (23 mL, 0.14 mol) was added slowly via syringe. The solution was then warmed to room temperature. N-[4(2-Pyrrolidin-1-ylpentanoyl)phenyl]acetamide hydrochloride (4o) (4.5 g, 18 mmol) was added over 20 min, and the mixture was heated to reflux for 1 h. The solution was cooled and then quenched cautiously with aqueous Na2SO3 (100 mL of a 1.6 M solution, 0.16 mol). The organics were separated and extracted into Et2O and then back-extracted into 1 M aqueous HCl. The acidic extracts were basified with 20% aqueous Na2CO3 to pH 8-9 and extracted into Et2O. The organic extracts were dried (MgSO4), filtered, and then treated with 2 M ethereal HCl. The resulting white precipitate was collected on a frit, dissolved in water, and then freeze dried to give pure 1-(4-nitrophenyl)-2-pyrrolidin-1-yl-pentan-1-one hydrochloride (4l) (290 mg, 5%); mp 189 °C dec. 1H NMR δ 10.8-10.6 (br, 1H), 8.45 (d, 2H), 8.32 (d, 2H), 5.65 (m, 1H), 3.7-3.3 (br, m, 2H), 3.3-3.1 (br, m, 2H), 2.1-1.8 (br, m, 6H), 1.4-1.2 (m, 1H), 1.1-0.9 (m, 1H), 0.78 (t, 3H); 13C NMR δ 196.0, 150.8, 138.7, 130.4, 124.3, 68.1, 53.9, 52.0, 31.2, 22.9, 17.2, 13.7; APCI MS m/z: 277 (M + 1). Anal. (C15H21ClN2O3‚1/2H2O.1/10HCl) C, H, N, Cl. 1-(4-Methoxyphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4m). 1-(4-Methoxyphenyl)pentan-1-one (2m), obtained by methylation of commercially available 1-(4-hydroxyphenyl)pentan-1-one (2k) with MeI/K2CO3 in refluxing acetone, was brominated (general procedure B) to afford 2-bromo-1-(4-methoxyphenyl)pentan-1-one (3m). 1H NMR δ 8.01 (d, 2H), 6.96 (d, 2H), 5.12 (dd, 1H), 3.89 (s, 3H), 2.25-2.05 (m, 2H), 1.65-1.35 (m, 2H), 0.98 (t, 3H). Compound 4m was obtained as a colorless solid from 3m (general procedure C) (68% yield). 1H NMR δ 10.810.6 (br, 1H), 8.10 (d, 2H), 7.15 (d, 2H), 5.55 (m, 1H), 3.89 (s, 3H), 3.7-3.55 (br, m, 1H), 3.55-3.4 (br, m, 1H), 3.3-3.15 (br, m, 1H), 3.1-2.95 (br, m, 1H), 2.15-1.85 (br, m, 6H), 1.34-1.15 (m, 1H), 1.15-1.0 (m, 1H), 0.79 (t, 3H); 13C NMR δ 194.7, 164.5, 131.4, 127.4, 114.5, 66.7, 55.8, 53.4, 51.8, 32.0, 22.9, 17.5, 13.7; APCI MS m/z: 262 (M + 1). Anal. (C16H24ClNO2‚1/2H2O.1/2HCl) C, H, N, Cl. 4-(2-Pyrrolidin-1-yl-pentanoyl)benzoic Acid Methyl Ester Hydrochloride (4n). 4-(2-Bromopentanoyl)benzoic acid methyl


ester (3n): 1H NMR δ 8.14 (d, 2H), 8.06 (d, 2H), 5.13 (t, 1H), 3.96 (s, 3H), 2.2-2.05 (m, 2H), 1.65-1.35 (m, 2H), 1.00 (t, 3H) was prepared (general procedure B) from 2n35 and converted to 4n as described in general procedure C (77% yield); mp 202 °C dec. 1H NMR δ 10.7-10.5 (br, 1H), 8.3-8.1 (m, 4H), 5.58 (m, 1H), 3.91 (s, 3H), 3.7-3.5 (br, m, 2H), 3.3-3.05 (br, m, 2H), 2.152.85 (br, m, 6H), 1.4-1.2 (m, 1H), 1.15-0.95 (m, 1H), 0.77 (t, 3H); 13C NMR δ 196.5, 165.3, 137.6, 134.6, 129.8, 129.2, 67.9, 53.9, 52.7, 51.9, 31.4, 22.9, 17.2, 13.7; APCI MS m/z: 290 ((M + 1), 100%), 275. Anal. (C17H24ClNO3) C, H, N, Cl. N-[4-(2-Pyrrolidin-1-yl-pentanoyl)phenyl]acetamide Hydrochloride (4o). N-(4-Pentanoylphenyl)acetamide (2o) prepared in 60% yield by Friedel-Crafts acylation of acetanilide in CS2 and purified by recrystallization from hot MeOH: 1H NMR δ 7.94 (d, 2H), 7.61 (d, 2H), 7.41 (br, s, 1H), 2.94 (t, 2H), 2.22 (s, 3H), 1.81.65 (m, 2H), 1.45-1.35 (m, 2H), 0.95 (t, 3H); 13C NMR δ 168.4, 142.0, 132.9, 129.5, 118.8, 38.2, 26.6, 24.8, 22.5, 14.0 was brominated (general procedure B) to provide N-[4-(2-bromopentanoyl)phenyl]acetamide (3o). 1H NMR δ 8.00 (d, 2H), 7.65 (br, m, 3H), 5.12 (dd, 1H), 2.23 (s, 3H), 2.2-2.05 (m, 2H), 1.7-1.35 (m, 2H), 0.98 (t, 3H). Compound 4o was prepared from 3o as described in general procedure C (56% yield); mp 195 °C dec. 1H NMR δ 10.76 (s, 1H), 10.55-10.35 (br, 1H), 8.05 (d, 2H), 7.85 (d, 2H), 5.5-5.4 (br, m, 1H), 3.7-3.55 (br, 1H), 3.5-3.3 (br, 1H), 3.3-3.15 (br, m, 1H), 3.15-3.0 (br, m, 1H), 2.13 (s, 3H), 2.1-1.8 (br, m, 6H), 1.3-1.15 (m, 1H), 1.15-1.0 (m, 1H), 0.79 (t, 3H); 13C NMR δ 194.8, 169.4, 145.4, 130.4, 128.8, 118.4, 67.0, 53.6, 51.9, 32.0, 24.2, 22.8, 17.4, 13.7; APCI MS m/z: 289 (M + 1). Anal. (C17H25ClN2O2‚1/2H2O) C, H, N, Cl. 2-Pyrrolidin-1-yl-1-(4-trifluoromethylphenyl)pentan-1-one Hydrochloride (4p). 1-(4-Trifluoromethylphenyl)pentan-1-one (2p) prepared in 95% yield from 4-trifluoromethylbenzonitrile (general procedure A): 1H NMR δ 8.06 (d, 2H), 7.43 (d, 2H), 3.00 (t, 2H), 1.74 (m, 2H), 1.41 (m, 2H), 0.96 (t, 3H) was brominated (general procedure B) to provide 2-bromo-1-(4-trifluoromethylphenyl)pentan-1-one (3p). 1H NMR δ 8.13 (d, 2H), 7.76 (d, 2H), 5.11 (dd, 1H), 2.25-2.1 (m, 2H), 1.7-1.4 (m, 2H), 1.00 (t, 3H). Compound 4p was prepared from 3p as described in general procedure C (44% yield); mp 228 °C dec. 1H NMR δ 10.8-10.6 (br, 1H), 8.28 (d, 2H), 8.03 (d, 2H), 5.62 (m, 1H), 3.7-3.4 (br, m, 2H), 3.3-3.05 (br, m, 2H), 2.1-1.8 (br, m, 6H), 1.4-1.2 (m, 1H), 1.1-0.9 (m, 1H), 0.78 (t, 3H); 13C NMR δ 196.2, 137.4, 129.7, 126.3, 67.8, 53.8, 51.9, 31.3, 22.9, 17.2, 13.7; APCI MS m/z: 300 (M + 1). Anal. (C16H21ClF3NO) C, H, N, Cl. 1-(4-Propynylphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4q). 1-(4-Iodophenyl)-2-pyrrolidin-1-yl-pentan-1-one hydrochloride (4g) (500 mg, 1.27 mmol) was taken up in Et2NH (10 mL) and degassed by purging with N2. [PdCl2(PPh3)2] (18 mg, 2.5 × 10-5 mol) and CuI (2.4 mg, 1.3 × 10-5 mol) were added to the stirring solution at room temperature. Propyne was then bubbled through the resulting yellow mixture for 7 h. The mixture was filtered and reduced to an oil in vacuo. The oil was taken up in Et2O and extracted into 1 M aqueous HCl and then back-extracted into Et2O by treatment with 20% aqueous Na2CO3 until pH 8-9. The organic extracts were dried (MgSO4), filtered, and reduced in vacuo to a pale-yellow oil. The hydrochloride was prepared from 2 M ethereal HCl and recrystallized twice from EtOH/Et2O to give pure 1-(4-propynylphenyl)-2-pyrrolidin-1-yl-pentan-1-one (4q) as a colorless, crystalline solid (260 mg, 67%); mp 231 °C dec. 1H NMR δ 10.6-10.4 (br, 1H), 8.04 (d, 2H), 7.62 (d, 2H), 5.55-5.4 (br, m, 1H), 3.7-3.55 (br, 1H), 3.55-3.4 (br, 1H), 3.3-3.1 (br, m, 1H), 3.1-2.95 (br, m, 1H), 2.12 (s, 3H), 2.1-1.8 (br, m, 6H), 1.3-1.15 (m, 1H), 1.15-0.95 (m, 1H), 0.78 (t, 3H);13C NMR δ 195.9, 133.1, 131.9, 129.9, 129.1, 92.1, 79.0, 67.5, 53.8, 51.9, 31.7, 22.8, 17.2, 13.7, 4.1; APCI MS m/z: 270 (M + 1). Anal. (C18H24ClNO) C, H, N, Cl. 1-(2-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4r). 1-(2-Methylphenyl)pentan-1-one (2r) obtained in 75% yield from 2-methylbenzonitrile (general procedure A) and purified by distillation (bp 58-60 °C, 0.05 mmHg): 1H NMR δ 7.62 (m, 1H), 7.36 (m, 1H), 7.26 (m, 2H), 2.89 (t, 2H), 2.48 (s,

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3H), 1.68 (m, 2H), 1.39 (m, 2H), 0.94 (t, 3H) was brominated (general procedure B) to afford 2-bromo-1-(2-tolyl)pentan-1-one (3r). 1H NMR δ 7.63 (d, 1H), 7.42 (m, 1H), 7.27 (m, 2H), 5.05 (dd, 1H), 2.50 (s, 3H), 2.25-2.0 (m, 2H), 1.65-1.35 (m, 2H), 0.99 (t, 3H). Compound 4r was prepared from 3r as described in general procedure C (39% yield). 1H NMR δ 10.9-10.7 (br, 1H), 8.12 (d, 1H), 7.58 (t, 1H), 7.44 (t, 2H), 5.56 (m, 1H), 3.7-3.5 (br, 2H), 3.35-3.1 (br, m, 2H), 2.46 (s, 3H), 2.1-1.7 (br, m, 6H), 1.4-1.2 (m, 1H), 1.1-0.9 (m, 1H), 0.76 (t, 3H); 13C NMR δ 199.1, 138.8, 134.4, 133.2, 132.3, 130.0, 126.2, 68.9, 53.5, 51.8, 31.4, 23.0, 20.7, 17.5, 13.7; APCI MS m/z: 246 (M + 1). Anal. (C16H24ClNO‚H2O) C, H, N, Cl. 1-(3-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4s). 1-(3-Methylphenyl)pentan-1-one (2s) obtained in 98% yield from 3-methylbenzonitrile (general procedure A) and purified by distillation (bp 64-68 °C, 0.1 mmHg): 1H NMR δ 7.86 (d, 2H), 7.26 (d, 2H), 2.94 (t, 2H), 2.41 (s, 3H), 1.71 (m, 2H), 1.41 (m, 2H), 0.95 (t, 3H) was brominated (general procedure B) to provide 2-bromo-1-(3-methylphenyl)pentan-1-one 3s. 1H NMR δ 7.81 (m, 2H), 7.40 (m, 2H), 5.15 (dd, 1H), 2.43 (s, 3H), 2.252.05 (m, 2H), 1.7-1.35 (m, 2H), 0.99 (t, 3H). Compound 4s was prepared from 3s as described in general procedure C (53% yield); mp 166 °C dec. 1H NMR δ 10.8-10.6 (br, 1H), 7.90 (d, 2H), 7.657.5 (m, 2H), 5.57 (m, 1H), 3.7-3.55 (br, 1H), 3.55-3.4 (br, 1H), 3.3-3.15 (br, m, 1H), 3.15-3.0 (br, m, 1H), 2.42 (s, 3H), 2.1-1.8 (br, m, 6H), 1.35-1.15 (m, 1H), 1.15-0.95 (m, 1H), 0.78 (t, 3H); 13C NMR δ 196.7, 138.8, 135.6, 134.5, 129.1, 126.1, 67.4, 53.6, 51.9, 31.7, 22.9, 20.8, 17.3, 13.7; APCI MS m/z: 246 (M + 1). Anal. (C16H24ClNO) C, H, N, Cl. 1-Naphthalen-2-yl-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4t). 1-Naphthalen-2-yl-pentan-1-one (2t) prepared in 95% yield from naphthalene-2-carbonitrile (general procedure A): 1H NMR δ 8.48 (s, 1H), 8.04 (dd, 1H), 7.97 (d, 1H), 7.90 (m, 2H), 7.57 (m, 2H), 3.11 (t, 2H), 1.79 (m, 2H), 1.44 (m, 2H), 0.98 (t, 3H) was brominated (general procedure B) to afford 2-bromo-1naphthalen-2-yl-pentan-1-one (3t). 1H NMR δ 8.55 (s, 1H), 8.17.85 (m, 4H), 7.60 (m, 2H), 5.33 (dd, 1H), 2.3-2.1 (m, 2H), 1.71.4 (m, 2H), 1.01 (t, 3H). Compound 4t was prepared from 3t as described in general procedure C (51% yield); mp 221-223 °C dec; 1H NMR δ 10.8-10.6 (br, 1H), 8.92 (s, 1H), 8.2-8.0 (m, 4H), 7.75 (dt, 2H), 5.73 (m, 1H), 3.75-3.6 (br, 1H), 3.6-3.4 (br, m, 1H), 3.35-3.1 (br, m, 2H), 2.2-1.8 (m, 6H), 1.4-1.2 (m, 1H), 1.2-1.0 (m, 1H), 0.78 (t, 3H); 13C NMR δ 196.6, 135.7, 132.0, 131.8, 131.7, 129.9, 129.7, 129.0, 127.8, 127.5, 123.4, 67.3, 53.6, 52.0. 31.9, 22.9, 17.4, 13.7; APCI MS m/z: 282 (M + 1). Anal. (C19H24ClNO) C, H, N, Cl. 1-(3,4-Dichlorophenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4u). 1-(3,4-Dichlorophenyl)pentan-1-one (2u) prepared in 93% yield from 3,4-dichlorobenzonitrile (general procedure A) and used crude in the next step of the reaction: 1H NMR δ 8.03 (d, 1H), 7.78 (dd, 1H), 7.54 (d, 1H), 2.92 (t, 2H), 1.71 (m, 2H), 1.39 (m, 2H), 0.94 (t, 3H) was brominated (general procedure B) to afford 2-bromo-1-(3,4-dichlorophenyl)pentan-1-one (3u). 1H NMR δ 8.09 (d, 1H), 7.84 (dd, 1H), 7.55 (d, 1H), 5.02 (dd, 1H), 2.25-2.05 (m, 2H), 1.65-1.35 (m, 2H), 0.99 (t, 3H). Compound 4u was prepared from 3u as described in general procedure C (32% yield); mp 195 °C dec; 1H NMR δ 10.8-10.6 (br, 1H), 8.35 (d, 1H), 8.04 (dd, 1H), 7.94 (d, 1H), 5.58 (m, 1H), 3.7-3.6 (br, 1H), 3.6-3.45 (br, m, 1H), 3.3-3.05 (br, m, 2H), 2.15-2.85 (br, m, 6H), 1.35-1.15 (m, 1H), 1.15-0.95 (m, 1H), 0.79 (t, 3H); 13C NMR δ 195.0, 137.8, 134.5, 132.3, 131.6, 130.8, 128.8, 67.5, 53.7, 51.9, 31.4, 22.9, 17.2, 13.6; APCI MS m/z: 300, 302, 304 (M + 1). Anal. (C15H20Cl3NO) C, H, N, Cl. 1-(3,4-Dihydroxyphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrobromide (4v). 1-(3,4-Dimethoxyphenyl)-2-pyrrolidin-1-yl-pentan-1-one (4w) (1.50 g, 4.6 mmol) was freed from its hydrochloride salt by treatment with aqueous Na2CO3 and extraction into CH2Cl2. The organics were dried (MgSO4), filtered, and reduced to a pale-yellow oil in vacuo. The oil was taken up in CH2Cl2 (10 mL) and cooled to -78 °C, whereon BBr3 (46 mL, 1.0 M solution in CH2Cl2, 46 mmol) was added dropwise over 0.5 h. The resulting

Meltzer et al.

yellow mixture was warmed slowly to room temperature and stirred for 3 h. The yellow solution was hydrolyzed cautiously with aqueous Na2CO3 (20% solution) until the pH was 8 and then water (50 mL) was added, and the solution was allowed to stand overnight. Neutral organics were extracted from the mixture by the separation of the CH2Cl2 layer, which was then discarded. The aqueous layer was acidified to pH 3 with 1 M HCl, most of the water was removed by rotary evaporation, and the remaining volume of ca. 10 mL was allowed to cool in the refrigerator. After 3 days, a white solid separated from the solution and was collected by filtration. Recrystallization (EtOH/Et2O) afforded pure 1-(3,4-dihydroxyphenyl)-2-pyrrolidin-1-yl-pentan-1-one (4v) as its hydrobromide, an off-white solid (0.60 g, 44%); mp 181-182 °C. 1H NMR δ 10.42 (s, 1H), 10.1-9.9 (br, 1H), 9.59 (s, 1H), 7.51 (dd, 1H), 7.43 (d, 1H), 6.91 (d, 1H), 5.35-5.25 (br, 1H), 3.75-3.5 (br, 1H), 3.5-3.3 (br, 1H), 3.3-3.15 (br, 1H), 3.0-2.85 (br, 1H), 2.1-1.8 (m, 6H), 1.3-1.0 (m, 2H), 0.80 (t, 3H); 13C NMR δ 194.8, 153.4, 146.4, 126.7, 123.5, 116.0, 115.9, 67.5, 54.5, 52.3, 32.8, 23.2, 17.9, 14.3; APCI MS m/z: 264 (M + 1). Anal. (C15H22BrNO3) C, H, N, Br. 1-(3,4-Dimethoxyphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4w). 2-Bromo-1-(3,4-dimethoxyphenyl)pentan-1-one (3w) was obtained together with 2-bromo-1-(2-bromo-4,5-dimethoxyphenyl)pentan-1-one by using general procedure B. The compounds were separated by flash column chromatography (10% EtOAc/hexane) to provide 2-bromo-1-(3,4-dimethoxyphenyl)-pentan-1-one (3w): 1H NMR δ 7.66 (dd, 1H), 7.58 (d, 1H), 6.91 (d, 1H), 5.15 (dd, 1H), 3.97 (s, 3H), 3.95 (s, 3H), 2.25-2.05 (m, 2H), 1.7-1.35 (m, 2H), 1.01 (t, 3H) and 2-bromo-1-(2-bromo-4,5dimethoxyphenyl)pentan-1-one: 1H NMR δ 7.07 (s, 1H), 7.04 (s, 1H), 5.28 (dd, 1H), 3.92 (s, 3H), 3.90 (s, 3H), 2.3-2.0 (m, 2H), 1.7-1.4 (m, 2H), 1.00 (t, 3H). Compound 4w was then prepared from 3w as described in general procedure C to provide a solid (74% yield); mp 177 °C dec. 1H NMR δ 10.5-10.3 (br, 1H), 7.78 (d, 1H), 7.53 (d, 1H), 7.18 (d, 1H), 5.55-5.4 (br, m, 1H), 3.90 (s, 3H), 3.86 (s, 3H), 3.7-3.55 (br, m, 1H), 3.5-3.3 (br, m, 1H), 3.33.15 (br, m, 1H), 3.05-2.9 (br, m, 1H), 2.1-1.8 (m, 6H), 1.3-1.0 (m, 2H), 0.80 (t, 3H); 13C NMR δ 194.7, 154.7, 149.0, 127.2, 124.6, 111.2, 110.5, 66.7, 56.0, 55.7, 53.7, 51.8, 32.1, 22.8, 17.4, 13.7; APCI MS m/z: 292 (M + 1). Anal. (C17H26ClNO3) C, H, N, Cl. 1-(4-Furan-2-ylphenyl)-2-pyrrolidin-1-yl-pentan-1-one Hydrochloride (4x). This compound was prepared using a procedure analogous to that described later for the preparation of 4z, except that commercially available 2-tributylstannyl furan was employed as a starting material, and chromatography was not performed on the crude free base. The crude hydrochloride was recrystallized from hot EtOH to give pure 4x as a colorless crystalline solid: (59% yield); mp 236 °C dec. 1H NMR (DMSO-d6 + 6 drops of CD3OD) δ 8.14 (d, 2H), 7.95 (d, 2H), 7.90 (d, 1H), 7.29 (d, 1H), 6.71 (dd, 1H), 5.51 (m, 1H), 3.7-3.6 (br, m, 1H), 3.6-3.45 (br, m, 1H), 3.35-3.2 (br, m, 1H), 3.15-3.0 (br, m, 1H), 2.15-1.85 (br, m, 6H), 1.35-1.15 (m, 1H), 1.15-1.0 (m, 1H), 0.81 (t, 3H); 13C NMR δ 195.7, 151.8, 145.1, 136.0, 132.6, 130.0, 123.8, 112.9, 109.9, 67.8, 54.2, 52.0, 32.0, 22.9, 17.3, 13.7; APCI MS m/z: 298 (M + 1). Anal. (C19H24ClNO2) C, H, N, Cl. 2-Pyrrolidin-1-yl-1-(4-thiophen-2-yl-phenyl)pentan-1-one Hydrochloride (4y). This compound was prepared using a procedure analogous to that described later for the preparation of 4z, except that commercially available 2-tributylstannyl thiophene was employed as a starting material, and chromatography was not performed on the crude free base. The crude hydrochloride was readily obtained by the treatment of the crude free base with 2 M ethereal HCl. Recrystallization from hot EtOH gave pure 4v as a colorless crystalline solid (61% yield); mp 220 °C dec. 1H NMR (DMSO-d6 + 12 drops of CD3OD) δ 8.12 (d, 2H), 7.93 (d, 2H), 7.77 (dd, 1H), 7.72 (dd, 1H), 7.23 (dd, 1H), 5.5-5.4 (br, 1H), 3.73.45 (br, m, 2H), 3.3-3.2 (br, m, 1H), 3.1-3.0 (br, m, 1H), 2.21.9 (br, m, 6H), 1.35-1.2 (m, 1H), 1.2-1.0 (m, 1H), 0.83 (t, 3H); 13C NMR δ 195.9, 141.8, 140.3, 132.9, 130.3, 129.3, 128.6, 126.6, 126.0, 68.1, 54.5, 52.1, 32.2, 23.1, 17.4, 13.8; APCI MS m/z: 314 (M + 1). Anal. (C19H24ClNOS) C, H, N, Cl.


1-(4-N-Methylpyrrolephenyl)-2-pyrrolidin-1-yl-pentan-1one Hydrochloride (4z). To a cooled (-78 °C) solution of N-methylpyrrole (1.14 g, 14 mmol) in THF (10 mL), tBuLi (9.1 mL of a 1.7 M solution in pentane, 15 mmol) was added dropwise. The mixture was then warmed to room temperature for 2 h and then cooled to -78 °C. Chlorotributylstannane (5.0 g, 15 mmol) was added to the mixture dropwise. On completion of addition, the mixture was warmed to room temperature and stirred for 1 h. The mixture was filtered and reduced to an oil in vacuo. This oil (crude 2-tributylstannyl-(N-methylpyrrole)) was added to a solution of 2-pyrrolidin-1-yl-1-(4-bromophenyl)-pentan-1-one (that had been freed from its hydrochloride 4f by treatment with 20% aqueous Na2CO3 and extraction into Et2O) in dioxane (30 mL). The resulting solution was degassed by purging with N2. [Pd(PPh3)4] (264 mg, 0.22 mmol) was added, and the mixture was heated to 95-100 °C (oil bath temperature) for a period of 10 h. The solvent was removed in vacuo. The pure free base was obtained by column chromatography (5% MeOH/CH2Cl2) as a yellow oil. The hydrochloride was prepared by treatment with 2 M ethereal HCl. Lyophilization of an aqueous solution of the salt afforded 1-(4-N-methylpyrrolephenyl)-2-pyrrolidin-1-yl-pentan-1-one hydrochloride as pale-green solid 4z (1.4 g, 36%); mp 185 °C. 1H NMR δ 10.6-10.45 (br, 1H), 8.11 (d, 2H), 7.72 (d, 2H), 7.00 (dd, 1H), 6.45 (dd, 1H), 6.15 (dd, 1H), 5.54 (m, 1H), 3.77 (s, 3H), 3.7-3.55 (br, 1H), 3.55-3.4 (br, 1H), 3.35-3.15 (br, m, 1H), 3.15-3.0 (br, m, 1H), 2.1-1.85 (br, m, 6H), 1.35-1.2 (m, 1H), 1.2-1.0 (m, 1H), 0.82 (t, 3H); 13C NMR δ 195.6, 139.1, 131.9, 131.5, 129.4, 127.4, 127.1, 111.1, 108.2, 67.2, 53.7, 51.9, 35.6, 31.9, 22.9, 17.4, 13.7; APCI MS m/z: 311 (M + 1). Anal. (C20H27ClN2O‚2/3H2O) C, H, N, Cl. 1-(4-Methylphenyl)pent-2-en-1-one (5a). This compound was prepared as described below for 5b, employing 2-bromo-1-(4methylphenyl)pentan-1-one (3a) as the starting material (82% yield).1H NMR δ 7.85 (d, 2H), 7.25 (d, 2H), 7.10 (dt, 1H), 6.88 (dt, 1H), 2.39 (s, 3H), 2.32 (m, 2H), 1.13 (t, 3H); 13C NMR δ 190.3, 150.6, 143.2, 135.3, 129.0, 128.5, 124.7, 25.7, 21.5, 12.2. 1-(3,4-Dichlorophenyl)pent-2-en-1-one (5b). 2-Bromo-1-(3,4dichlorophenyl) pentan-1-one (3u) (3.36 g, 10.9 mmol) was dissolved in DMF (60 mL). Li2CO3 (1.28 g, 17 mmol) and LiBr (0.99 g, 11.5 mmol) were added to the solution, which was then heated with stirring to 110-120 °C (oil bath temperature) for 1.5 h. The mixture was diluted with H2O (100 mL), and the organics were extracted into EtOAc (3 × 50 mL). The ethyl acetate layer was collected and washed with saturated brine (2 × 50 mL), dried (MgSO4), filtered, and reduced to an oil in vacuo. Flash column chromatography (1% EtOAc/hexane to 2.5% EtOAc/hexane) furnished pure 5b as a colorless solid (1.5 g, 60%). 1H NMR δ 8.01 (d, 1H), 7.76 (dd, 1H), 7.55 (d, 1H), 7.15 (dt, 1H), 6.80 (dt, 1H), 2.37 (m, 2H), 1.15 (t, 3H); 13C NMR δ 188.5, 152.8, 137.6, 137.1, 133.2, 130.6, 130.5, 127.5, 124.1, 26.0, 12.2. 1-(3,4-Dichlorophenyl)-3-pyrrolidin-1-yl-pentan-1-one Hydrochloride (6b). 1-(3,4-Dichlorophenyl)pent-2-en-1-one (5b) (1.29 g, 5.63 mmol) was taken up in EtOH (10 mL), cooled on an ice bath, and degassed by purging with N2. Pyrrolidine (0.80 g, 11 mmol) was added dropwise over 2 min. After 0.5 h, the ethanolic solution was separated between 1 M aqueous HCl and Et2O. The HCl extracts were collected and back-extracted into Et2O by treatment with 20% aqueous Na2CO3. The ethereal extracts were dried (MgSO4), filtered, and treated with 2 M ethereal HCl. Trituration afforded 1-(3,4-dichlorophenyl)-2-pyrrolidin-1-yl-methylpentan-1-one hydrochloride 6b as a white powder, which was filtered and washed copiously with Et2O (0.99 g, 50%); mp 104107 °C dec. 1H NMR δ 11.1-10.9 (br, 1H), 8.27 (d, 1H), 7.98 (dd, 1H), 7.87 (d, 1H), 3.9-3.35 (br, m, 5H), 3.15-2.95 (br, 2H), 2.05-1.8 (br, m, 5H), 1.8-1.6 (m, 1H), 0.90 (t, 3H); 13C NMR δ 195.0, 136.4, 136.1, 131.8, 131.1, 130.3, 128.1, 59.2, 50.7, 50.1, 38.2, 23.8, 22.9, 10.0; APCI MS m/z: 300, 302, 304 (M + 1). Anal. (C15H20Cl3NO‚1/3H2O) C, H, N, Cl. 1-(4-Methylphenyl)-3-pyrrolidin-1-yl-pentan-1-one Hydrochloride (6a). This compound was prepared from 1-(4-methylphenyl)-2-en-1-one (5a) using the same procedure as that described for 6b; mp 97 °C dec. 1H NMR δ 11.1-10.9 (br, 1H), 7.94 (d,


2H), 7.38 (d, 2H), 3.9-3.75 (br, 1H), 3.7-3.6 (m, 1H), 3.6-3.3 (m, 3H), 3.15-2.95 (br, m, 2H), 1.96 (s, 3H), 2.0-1.8 (br, m, 5H), 1.8-1.6 (m, 1H), 0.88 (t, 3H); 13C NMR δ 196.2, 144.3, 133.5, 129.3, 128.3, 59.7, 50.7, 50.4, 37.9, 23.8, 22.9, 22.8, 21.2, 9.9; APCI MS m/z: 246 (M + 1). Anal. (C16H24ClNO) C, H, N, Cl. 1-(3,4-Dichlorophenyl)-2-pyrrolidin-1-yl-methylpentan-1one Hydrochloride (7b). 2-Bromo-1-(3,4-dichlorophenyl)pentan1-one (3u) (3.5 g, 15 mmol), pyrrolidine.HCl (2.4 g, 23 mmol), and paraformaldehyde (1.35 g, 45 mmol) were taken up in iPrOH (25 mL) containing concentrated HCl (0.2 mL). The mixture was brought to reflux for 16 h. The solvent was removed by rotary evaporation, and the residue was separated between 1 M aqueous HCl and Et2O. The aqueous extracts were basified with 20% aqueous Na2CO3 to pH 8-9, and the organics were extracted into Et2O. The organics were dried (MgSO4), filtered, and reduced to an oil in vacuo. Column chromatography (10% MeOH/CH2Cl2) gave the pure free base. Reaction with 2 M ethereal HCl and filtration of the resulting white precipitate provided 1-(3,4-dichlorophenyl)-2-pyrrolidin-1-yl-methylpentan-1-one hydrochloride (7b) (0.61 g, 12%); mp 168 °C dec; 1H NMR δ 10.7-10.5 (br, 1H), 8.29 (d, 1H), 8.05 (dd, 1H), 7.88 (d, 1H), 4.3-4.1 (br, 1H), 3.73.5 (br, m, 2H), 3.5-3.25 (br, m, 2H), 3.15-2.85 (br, m, 2H), 2.11.75 (br, m, 4H), 1.75-1.4 (m, 2H), 1.35-1.05 (m, 2H), 0.81 (t, 3H); 13C NMR δ 198.9, 136.6, 135.9, 132.1, 131.4, 131.2, 130.5, 130.3, 128.7, 128.5, 54.1, 53.4, 42.3, 42.2, 33.1, 22.7, 22.4, 18.8, 13.8; APCI MS m/z: 314, 312, 310 (M + 1). Anal. (C16H22Cl3NO) C, H, N, Cl. 1-(4-Methylphenyl)-2-pyrrolidin-1-yl-methylpentan-1-one Hydrochloride (7a). This compound was prepared from 1-(2methylphenyl)pentan-1-one (3.5 g, 20 mmol) using the same method described for 7b with the following modifications. No chromatography was performed. The hydrochloride salt of the crude free base was isolated after extraction of the crude reaction mixture into 1 M aqueous HCl and back extraction (with 20% aqueous Na2CO3) into Et2O, followed by acidification with 2 M HCl in Et2O. The product was recrystallized from EtOH/Et2O to give pure crystalline 1-(4-methylphenyl)-2-pyrrolidin-1-yl-methylpentan-1-one hydrochloride (7a) (2.6 g, 44%); mp 176 °C dec. 1H NMR δ 10.8-10.6 (br, 1H), 7.98 (d, 2H), 7.39 (d, 2H), 4.25-4.15 (br, m, 1H), 3.653.5 (m, 2H), 3.5-3.25 (m, 2H), 3.1-2.95 (br, m, 1H), 2.95-2.8 (br, m, 1H), 2.40 (s, 3H), 2.0-1.75 (m, 4H), 1.7-1.4 (m, 2H), 1.3-1.1 (m, 2H), 0.81 (t, 3H); 13C NMR δ 200.4, 144.4, 135.2, 129.7, 129.5, 128.7, 128.5, 54.0, 53.7, 53.3, 41.9, 33.5, 22.8, 22.3, 21.1, 19.0, 13.8; APCI MS m/z: 260 (M + 1). Anal. (C17H26ClNO) C, H, N, Cl. 1-(3,4-Dichlorophenyl)-2-pyrrolidin-1-yl-butan-1-one Hydrochloride (9a). 1-(3,4-Dichlorophenyl)butan-1-one prepared in quantitative yield from 3,4-dichlorobenzonitrile and n-PrMgCl (general procedure A); 1H NMR δ 8.01 (d, 1H), 7.78 (dd, 1H), 7.54 (d, 1H), 2.91 (t, 2H), 1.77 (sextet, 2H), 1.01 (t, 3H) was brominated according to general procedure B to give 2-bromo-1(3,4-dichlorophenyl)butan-1-one. 1H NMR δ 8.09 (d, 1H), 7.84 (dd, 1H), 7.57 (d, 1H), 4.95 (dd, 1H), 2.35-2.05 (m, 2H), 1.09 (t, 3H). Compound 9a was prepared according to general procedure C (71% yield); mp 211 °C dec. 1H NMR δ 10.95-10.75 (br, 1H), 8.35 (d, 1H), 8.06 (dd, 1H), 7.92 (d, 1H), 5.75-5.65 (br, m, 1H), 3.653.35 (br, m, 2H), 3.3-3.1 (br, m, 2H), 2.15-1.9 (br, m, 6H), 0.78 (t, 3H); 13C NMR δ 194.7, 137.7, 134.5, 132.3, 131.6, 130.7, 128.8, 68.5, 53.7, 51.8, 23.0, 22.6, 8.4; APCI MS m/z: 286, 288, 290 (M + 1). Anal. (C14H18Cl3NO) C, H, N. 4-Methyl-2-pyrrolidin-1-yl-1-(4-methylphenyl)pentan-1-one Hydrochloride (9b). 4-Methyl-1-(4-methylphenyl)pentan-1-one prepared in quantitative yield by Friedel-Crafts acylation of toluene with 4-methylvaleroyl chloride: 1H NMR δ 7.86 (d, 2H), 7.26 (d, 2H), 3.94 (t, 2H), 2.41 (s, 3H), 1.62 (m, 3H), 0.94 (d, 6H) was converted to 2-bromo-4-methyl-1-(4-methylphenyl)pentan-1-one, as described in general procedure B. 1H NMR δ 7.92 (d, 2H), 7.29 (d, 2H), 5.21 (dd, 1H), 2.43 (s, 3H), 2.15-1.95 (m, 2H), 1.951.75 (m, 1H), 0.96 (d, 6H). 4-Methyl-2-pyrrolidin-1-yl-1-(4methylphenyl)pentan-1-one hydrochloride (9b) was then prepared as described in general procedure C (68% yield); mp 218 °C dec;

1430 1H


NMR δ 10.9-10.75 (br, 1H), 8.06 (d, 2H), 7.45 (d, 2H), 5.46 (m, 1H), 3.75-3.6 (br, 1H), 3.6-3.4 (br, 1H), 3.3-3.0 (br, m, 2H), 2.42 (s, 3H), 2.1-1.7 (m, 6H), 1.45-1.3 (m, 1H), 0.82 (dd, J ) 2, 6 Hz, 6H); 13C NMR δ 197.2, 164.0, 132.9, 129.9, 129.0, 64.4, 52.7, 51.2, 24.2, 23.3, 22.8, 21.5, 21.3; APCI MS m/z: 260 (M + 1). Anal. (C17H26ClNO) C, H, N, Cl. 1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pent-4-ene-1-one Hydrochloride (9c). This compound was prepared as described previously;29 mp 196 °C dec. 1H NMR δ 10.8-10.6 (br, 1H), 7.96 (d, 2H), 7.43 (d, 2H), 5.8-5.6 (m, 2H), 5.03 (s, 1H), 5.00 (m, 1H), 3.75-3.6 (br, 1H), 3.6-3.4 (br, 1H), 3.4-3.2 (br, m, 1H), 3.153.0 (br, m, 1H), 3.85-3.65 (br, m, 2H), 2.42 (s, 3H), 2.2-1.85 (br, m, 4H); 13C NMR δ 195.2, 145.8, 131.8, 130.6, 129.7, 129.0, 120.1, 66.9, 53.8, 52.0, 34.2, 22.9, 21.3; APCI MS m/z: 244 (M + 1). Anal. (C16H22ClNO) C, H, N, Cl. 1-(3,4-Dichlorophenyl)-2-pyrrolidin-1-yl-pent-4-ene-1-one Hydrochloride (9d). This compound was prepared as described for 9c;29 mp 176 °C dec; 1H NMR δ 10.8-10.6 (br, 1H), 8.29 (d, 1H), 8.00 (dd, 1H), 7.94 (d, 1H), 5.8-5.6 (m, 2H), 5.07 (s, 1H), 5.02 (m, 1H), 3.75-3.6 (br, m, 1H), 3.6-3.3 (br, m, 1H), 3.3-3.1 (br, m, 2H), 2.77 (m, 2H), 2.2-1.8 (br, m, 4H); 13C NMR δ 194.2, 137.8, 134.4, 132.2, 131.6, 130.8, 130.3, 128.8, 120.6, 67.2, 53.9, 52.1, 33.8, 22.9; APCI MS m/z: 302 ((M + 1), 100%), 300, 298. Anal. (C15H18Cl3NO) C, H, N, Cl. 1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pent-4-yn-1-one Hydrochloride (9e). 1-(4-Methylphenyl)-2-pyrrolidin-1-ylethanone (8)29 (25 g, 104 mmol) was freed from its hydrochloride by treatment with aqueous Na2CO3 and extraction into Et2O. The organics were dried (MgSO4), filtered, and reduced in vacuo to a yellow oil. This oil was taken up in toluene (200 mL), and NaNH2 was added to the stirring solution, which was then heated to approximately 120 °C (oil bath temperature) for 0.5 h. The solution was allowed to cool to about 100 °C, and propargyl bromide (13 mL, 80% w/w solution in toluene, 14 g, 115 mmol) was added to the orange mixture at a rate such that steady reflux was maintained with concomitant NH3 evolution. Upon complete addition (0.5 h), the mixture was allowed to cool to room temperature and was then hydrolyzed cautiously by the addition of water (100 mL). The toluene layer was separated, and the aqueous layer was extracted with toluene (2 × 50 mL). The combined organics were dried (MgSO4), filtered, and reduced in vacuo to a brown oil that was taken up in Et2O (50 mL). HCl (2 M) in Et2O was added to the ethereal solution of the oil. Trituration afforded a brown solid that could not be crystallized from EtOH/Et2O. The solvents were removed in vacuo, and the free base was prepared by the addition of 2 M NaOH solution until pH 8-9 was reached. The organics were extracted into Et2O (3 × 100 mL) to give a light-brown solution. Back-extraction into 1 M HCl (3 × 50 mL) gave a lightyellow solution. The water was removed by rotary evaporation; lyophilization then gave a light-brown gum (5.3 g). Recrystallization from EtOH/Et2O afforded pure 1-(4-methylphenyl)-2-pyrrolidin1-yl-pent-4-yn-1-one hydrochloride (9e) (3.15 g, 11%); mp 178 °C dec. 1H NMR δ 10.6-10.4 (br, 1H), 7.97 (d, 2H), 7.45 (d, 2H), 5.66 (m, 1H), 3.7-3.2 (m, 3H), 3.2-2.9 (m, 4H), 2.43 (s, 3H), 2.1-1.8 (m, 4H); 13C NMR δ 193.9, 146.0, 131.1, 129.7, 129.2, 76.8, 76.6, 65.2, 54.0, 52.0, 22,9, 22.9, 21.3, 20.0; APCI MS m/z: 242 (M + 1). Anal. (C16H20ClNO) C, H, N, Cl. 2-Butylamin-1-yl-1-(3,4-dichlorophenyl)pentan-1-one Hydrochloride (9f). Compound 9f (an off-white solid) was obtained from 3u (described above) and n-butylamine, according to general procedure C (71% yield); mp 185 °C dec. 1H NMR δ 9.8-9.6 (br, 1H), 9.3-9.1 (br, 1H), 8.35 (d, 1H), 8.04 (dd, 1H), 7.91 (d, 1H), 5.4-5.25 (br, 1H), 3.05-2.75 (br, m, 2H), 2.05-1.8 (br, m, 2H), 1.8-1.6 (br, m, 2H), 1.4-1.2 (m, 3H), 1.2-1.0 (m, 1H), 0.88 (t, 3H), 0.78 (t, 3H); 13C NMR δ 194.8, 137.6, 134.3, 132.3, 131.5, 130.6, 128.7, 60.8, 45.7, 31.5, 27.4, 19.3, 17.2, 13.6, 13.5; APCI MS m/z: 302, 304, 306 (M + 1). Anal. (C15H22Cl3NO) C, H, N, Cl. 1-(3,4-Dichlorophenyl)-2-piperidin-1-yl-pentan-1-one Hydrochloride (9g). Compound 9g was prepared from 3u (described above) and piperidine, as described in general procedure C (35%

Meltzer et al.

yield); mp 202 °C dec. 1H NMR δ 10.5-10.3 (br, 1H), 8.40 (d, 1H), 8.10 (dd, 1H), 7.94 (d, 1H), 5.45-5.35 (br, m, 1H), 3.7-3.55 (br, m, 1H), 3.45-3.3 (br, m, 1H), 3.2-1.95 (br, m, 2H), 2.11.65 (br, m, 7H), 1.5-1.3 (br, 1H), 1.2-1.0 (br, m, 2H), 0.81 (t, 3H); 13C NMR δ 195.3, 138.0, 135.3, 132.4, 131.6, 130.7, 128.8, 65.8, 52.0, 50.2, 29.3, 22.3, 22.0, 21.5, 17.8, 13.7; APCI MS m/z: 314, 316, 318 (M + 1). Anal. (C16H22Cl3NO) C, H, N, Cl. 1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-ol Hydrochloride (Diastereoisomers 9h and 9j). 1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one hydrochloride (4a) (1.50 g, 5.32 mmol) was suspended in THF (20 mL). LiAlH4 (0.20 g, 5.3 mmol) was added in several small portions at room temperature to the stirring mixture with slight heat evolution. The resulting clear solution was hydrolyzed cautiously with H2O and then made acidic by the addition of 1 M aqueous HCl. The aqueous extracts were collected and basified to pH 8-9 with 20% aqueous Na2CO3. The organics were extracted into Et2O, dried (MgSO4), filtered, and reduced to an oil in vacuo. Chromatography (5% NEt3/15% EtOAc/80% hexane) gave the two diastereoisomers 9h and 9j. The hydrochlorides were prepared from 2 M ethereal HCl and recrystallized from EtOH/Et2O to afford 1-(4-methylphenyl)-2-pyrrolidin-1-yl-pentan1-ol hydrochloride 9h, a colorless crystalline solid (0.57 g, 37%); mp 140-142 °C. 1H NMR δ 10.15-10.0 (br, 1H), 7.32 (d, 2H), 7.19 (d, 2H), 6.20 (d, J ) 5 Hz, 1H), 5.24 (s, 1H), 3.75-3.65 (br, m, 1H), 3.65-3.5 (br, m, 1H), 3.4-3.3 (br, 2H), 3.2-3.05 (br, m, 1H), 2.30 (s, 3H), 2.1-1.8 (br, m, 4H), 1.75-1.6 (m, 1H), 1.41.25 (br, m, 1H), 1.1-0.95 (m, 1H), 0.8-0.6 (m, 1H), 0.57 (t, 3H); 13C NMR δ 138.3, 136.2, 128.6, 125.5, 69.3, 68.1, 51.5, 26.5, 22.7, 22.5, 20.7, 20.3, 13.7; APCI MS m/z: 248 (M + 1). Anal. (C16H26ClNO) C, H, N, Cl and 1-(4-methylphenyl)-2-pyrrolidin-1-ylpentan-1-ol hydrochloride (9j), a colorless microcrystalline solid (159 mg, 10%); this was the more polar material; mp 219 °C dec. 1H NMR δ 9.8-9.65 (br, 1H), 7.33 (d, 2H), 7.20 (d, 2H), 6.53 (d, J ) 4 Hz, 1H), 4.65 (dd J ) 4, 9 Hz, 1H), 3.55-3.3 (m, 3H), 3.3-3.15 (br, m, 1H), 3.15-2.95 (br, m, 1H), 2.31 (s, 3H), 2.01.85 (br, 4H), 1.55-1.35 (br, m, 2H), 1.05-0.85 (m, 1H), 1.751.6 (m, 4H);13C NMR δ 138.4, 137.3, 128.9, 127.1, 72.1, 67.0, 40.3, 40.1, 27.6, 23.3, 23.0, 20.8, 20.0, 13.6; APCI MS m/z: 248 (M + 1). Anal. (C16H26ClNO) C, H, N, Cl. Biological Procedures. (Provided by NIDA from Oregon Health & Science University and SRI International). Unknowns were weighed and dissolved in DMSO to make a 10 mM stock solution. An initial dilution to 50 µM in assay buffer for binding or to 1 mM in assay buffer for uptake was made. Subsequent dilutions were made with assay buffer supplemented with DMSO, maintaining a final concentration of 0.1% DMSO. Pipetting was conducted using a Biomek 2000 robotic workstation. Inhibition of the Radioligand Binding of [125I]RTI 55 to hDAT, hSERT, or hNET in Clonal Cells. Cell preparation: HEK293 cells expressing hDAT, hSERT, or hNET inserts are grown to 80% confluence on 150-mm-diameter tissue culture dishes and serve as the tissue source. Cell membranes are prepared as follows. The medium is poured off the plate, and the plate is washed with 10 mL of calcium- and magnesium-free phosphate-buffered saline. The lysis buffer (10 mL; 2 mM HEPES with 1 mM EDTA) is added. After 10 min, the cells are scraped from plates, poured into centrifuge tubes, and centrifuged 30 000g for 20 min. The supernatant fluid is removed, and the pellet is resuspended in 1232 mL of 0.32 M sucrose using a Polytron at setting 7 for 10 s. The resuspension volume depends on the density of binding sites within a cell line and is chosen to reflect binding of 10% or less of the total radioactivity. Assay conditions: Each assay tube contains 50 µL of membrane preparation (about 10-15 µg of protein), 25 µL of an unknown, compound used to define nonspecific binding, or the buffer (Krebs-HEPES, pH 7.4; 122 mM NaCl, 2.5 mM CaCl2, 1.2 mM MgSO4, 10 µM pargyline, 100 µM tropolone, 0.2% glucose, and 0.02% ascorbic acid, buffered with 25 mM HEPES), 25 µL of [125I]RTI-55 (40-80 pM final concentration), and additional buffer sufficient to bring up the final volume to 250 µL. Membranes are preincubated with unknowns for 10 min prior to the addition of the [125I]RTI-55. The assay tubes are incubated at


25 °C for 90 min. Binding is terminated by filtration over GF/C filters using a Tomtec 96-well cell harvester. Filters are washed for 6 s with ice-cold saline. Scintillation fluid is added to each square, and the radioactivity remaining on the filter is determined using a Wallac µ- or β-plate reader. Specific binding is defined as the difference in binding observed in the presence and absence of 5 µM mazindol (HEK-hDAT and HEK-hNET) or 5 µM imipramine (HEK-hSERT). Two or three independent competition experiments are conducted with duplicate determinations. A GraphPAD Prism program is used to analyze the ensuing data, with IC50 values converted to Ki values using the Cheng-Prusoff equation (Ki ) IC50/(1+([RTI-55]/Kd RTI-55))). Filtration Assay for Inhibition of [3H]Neurotransmitter Uptake in HEK293 Cells Expressing Recombinant Biogenic Amine Transporters. Cell preparation: Cells are grown to confluence as described above. The medium is removed, and the cells are washed twice with phosphate buffered saline (PBS) at room temperature. Following the addition of 3 mL of KrebsHEPES buffer, the plates are warmed in a 25 °C water bath for 5 min. The cells are gently scraped and then triturated with a pipet. Cells from multiple plates are combined. One plate provides enough cells for 48 wells, which is required to generate data on two complete curves for the unknowns. Uptake inhibition assay conditions: The assay is conducted in 96 1-mL vials. Krebs-HEPES (350 µL) and unknowns, compounds used to define nonspecific uptake, or buffer (50 µL) are added to vials and placed in a 25 °C water bath. Specific uptake is defined as the difference in uptake observed in the presence and the absence of 5 µM mazindol (HEK-hDAT and HEK-hNET) or 5 µM imipramine (HEK-hSERT). Cells (50 µL) are added and preincubated with the unknowns for 10 min. The assay is initiated by the addition of [3H]dopamine, [3H]serotonin, or [3H]norepinephrine (50 µL, 20 nM final concentration). Filtration through Whatman GF/C filters presoaked in 0.05% polyethylenimine is used to terminate uptake after 10 min. The IC50S are calculated applying the GraphPAD Prism program to triplicate curves made up of six drug concentrations each. Two or three independent determinations of each curve are made.

Acknowledgment. This work was supported by the National Institute on Drug Abuse: DA1-8825 (P.M.), DA11542 (P.M.), DA06303 (B.K.M.), DA11558 (B.K.M.), DA15305 (B.K.M.), and RR00168 (B.K.M.). We thank the National Institute on Drug Abuse for providing the biological procedures and transporterinhibition binding data (DA 0007; Oregon Health & Science University), receptor binding and functional data (DA 1-8816; SRI International), and locomotor activity (DA 2-8822; University of North Texas Health Sciences). We thank Richard Laura for help with manuscript preparation. Supporting Information Available: Results from elemental analysis. This material is available free of charge via the Internet at http://pubs.acs.org. CCDC 280869-280870 contains the supplementary crystallographic data for this article. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

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